They are composed mostly of iron. They are composed mostly of ice. They regularly revolve near the Sun. They regularly replenish water on Earth.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which property is thought to characterize objects in the Oort Cloud?
Possibilities:
- They are composed mostly of iron.
- They are composed mostly of ice.
- They regularly revolve near the Sun.
- They regularly replenish water on Earth.

They are composed mostly of ice.