a wolf's howl an insect's coloring a fish's fin a squirrel storing acorns
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following is an example of a structural adaptation?
Possibilities:
- a wolf's howl
- an insect's coloring
- a fish's fin
- a squirrel storing acorns

a fish's fin