diff --git a/uroboros/command.py b/uroboros/command.py
index 1f15f8b..b32f61c 100644
--- a/uroboros/command.py
+++ b/uroboros/command.py
@@ -121,7 +121,7 @@ class Command(metaclass=abc.ABCMeta):
                 name=cmd.name,
                 description=cmd.long_description,
                 help=cmd.short_description,
-                parents=[o.get_parser() for o in cmd.options],
+                parents=[o.get_parser() for o in cmd.get_options()],
             )
             cmd.initialize(sub_parser)
 
@@ -129,7 +129,7 @@ class Command(metaclass=abc.ABCMeta):
         parser = argparse.ArgumentParser(
             prog=self.name,
             description=self.long_description,
-            parents=[o.get_parser() for o in self.options]
+            parents=[o.get_parser() for o in self.get_options()]
         )
         parser.set_defaults(func=self.run)
         return parser

diff --git a/tests/test_command.py b/tests/test_command.py
index b80b64f..a7eb5f0 100644
--- a/tests/test_command.py
+++ b/tests/test_command.py
@@ -4,6 +4,7 @@ from unittest import mock
 
 import pytest
 
+from uroboros import Option
 from uroboros.errors import CommandDuplicateError
 from .base import RootCommand, SecondCommand, ThirdCommand
 
@@ -318,3 +319,22 @@ class TestCommand(object):
         for cmd in commands:
             key = "after_validate_{}".format(cmd.name)
             assert getattr(args, key, None) == cmd.value
+
+    def test_create_default_parser(self):
+        class Opt(Option):
+            def build_option(self, parser):
+                parser.add_argument("--test", type=str)
+                return parser
+
+        class Cmd(RootCommand):
+            options = [Opt()]
+
+        class Cmd2(RootCommand):
+            def get_options(self):
+                return [Opt()]
+
+        argv = ["--test", "test"]
+        for cmd in [Cmd(), Cmd2()]:
+            cmd_parser = cmd.create_default_parser()
+            args = cmd_parser.parse_args(argv)
+            assert args.test == 'test'

`Command.get_options()` does not work well
### Expected

```python
class SomeOption(uroboros.Option):
    def build_option(self, parser):
        parser.add_argument('--opt', type=str)
        return parser

class HelloCommand(uroboros.Command):

    def get_options():
        return [SomeOption()]

HelloCommand().execute()
```

Now, `--opt` can be used.

### Actual

`--opt` does not be appeared in help message, and cannot parse it.


tests/test_command.py::TestCommand::test_create_default_parser
tests/test_command.py::TestCommand::test_build_option[command0] tests/test_command.py::TestCommand::test_build_option[command1] tests/test_command.py::TestCommand::test_build_option[command2] tests/test_command.py::TestCommand::test_validate[command0] tests/test_command.py::TestCommand::test_validate[command1] tests/test_command.py::TestCommand::test_validate[command2] tests/test_command.py::TestCommand::test_increment_nest[command_set0] tests/test_command.py::TestCommand::test_increment_nest[command_set1] tests/test_command.py::TestCommand::test_increment_nest[command_set2] tests/test_command.py::TestCommand::test_register_parent[command_set0] tests/test_command.py::TestCommand::test_register_parent[command_set1] tests/test_command.py::TestCommand::test_register_parent[command_set2] tests/test_command.py::TestCommand::test_add_command[command_set0] tests/test_command.py::TestCommand::test_add_command[command_set1] tests/test_command.py::TestCommand::test_add_command[command_set2] tests/test_command.py::TestCommand::test_multiple_add_command[root_cmd0-add_commands0] tests/test_command.py::TestCommand::test_multiple_add_command[root_cmd1-add_commands1] tests/test_command.py::TestCommand::test_add_others tests/test_command.py::TestCommand::test_get_all_sub_commands[command_set0] tests/test_command.py::TestCommand::test_get_all_sub_commands[command_set1] tests/test_command.py::TestCommand::test_get_all_sub_commands[command_set2] tests/test_command.py::TestCommand::test_get_all_sub_commands[command_set3] tests/test_command.py::TestCommand::test_get_sub_commands[command_set0-argv0] tests/test_command.py::TestCommand::test_get_sub_commands[command_set1-argv1] tests/test_command.py::TestCommand::test_get_sub_commands[command_set2-argv2] tests/test_command.py::TestCommand::test_get_sub_commands[command_set3-argv3] tests/test_command.py::TestCommand::test_get_sub_commands[command_set4-argv4] tests/test_command.py::TestCommand::test_add_duplicate_command[command_set0] tests/test_command.py::TestCommand::test_add_duplicate_command[command_set1] tests/test_command.py::TestCommand::test_execute[command_set0-root tests/test_command.py::TestCommand::test_execute[command_set1-root tests/test_command.py::TestCommand::test_execute[command_set2-root-False] tests/test_command.py::TestCommand::test_execute[command_set3-root tests/test_command.py::TestCommand::test_execute[command_set4-root tests/test_command.py::TestCommand::test_execute[command_set5-root-False] tests/test_command.py::TestCommand::test_violates_validation_argv[command_set0-root tests/test_command.py::TestCommand::test_violates_validation_argv[command_set1-root tests/test_command.py::TestCommand::test_violates_validation_argv[command_set2-root tests/test_command.py::TestCommand::test_violates_validation_argv[command_set3-root tests/test_command.py::TestCommand::test_violates_validation_argv[command_set4-root tests/test_command.py::TestCommand::test_violates_validation_argv[command_set5-root tests/test_command.py::TestCommand::test_before_validate tests/test_command.py::TestCommand::test_pre_hook[commands0] tests/test_command.py::TestCommand::test_pre_hook[commands1] tests/test_command.py::TestCommand::test_pre_hook[commands2] tests/test_command.py::TestCommand::test_after_validate tests/test_command.py::TestCommand::test_pre_hook_validated[commands0] tests/test_command.py::TestCommand::test_pre_hook_validated[commands1] tests/test_command.py::TestCommand::test_pre_hook_validated[commands2]