Rocks have many scratches. Rocks contain fossils. Rocks are covered by moss. Rocks are deep underground.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Rocks sometimes show evidence of ancient glaciers. Which is the best sign that glaciers once covered an area?
Possibilities:
- Rocks have many scratches.
- Rocks contain fossils.
- Rocks are covered by moss.
- Rocks are deep underground.

Rocks have many scratches.