the ability to live in salt water the ability to use oxygen in respiration the ability to cope with daily dry periods the ability to blend into the surroundings
I gave my students this multiple choice question: What adaptation is necessary in intertidal ecosystems but not in reef ecosystems?

Only one answer is correct among these 4 choices:
- the ability to live in salt water
- the ability to use oxygen in respiration
- the ability to cope with daily dry periods
- the ability to blend into the surroundings

Could you tell me which one is correct?

the ability to cope with daily dry periods