learned behavior migration instinct response to stimuli reproductive strategy
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: When the soil is saturated, earthworms move to the top of the soil to obtain oxygen. This behavior is evidence of which biological concept in earthworms?
Possibilities:
- learned behavior
- migration instinct
- response to stimuli
- reproductive strategy

response to stimuli