they will stop producing energy. they were formed millions of years ago. they are always available to produce energy. they take millions of years to start producing energy.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Wind and water are examples of renewable energy sources because
Possibilities:
- they will stop producing energy.
- they were formed millions of years ago.
- they are always available to produce energy.
- they take millions of years to start producing energy.

they are always available to produce energy.