birds flying south in the winter plants flowering in the summer trees losing their leaves in the fall earthworms living underground all year
I gave my students this multiple choice question: Which of the following is an example of organisms becoming dormant?

Only one answer is correct among these 4 choices:
- birds flying south in the winter
- plants flowering in the summer
- trees losing their leaves in the fall
- earthworms living underground all year

Could you tell me which one is correct?

trees losing their leaves in the fall