nervous and digestive nervous and circulatory respiratory and digestive respiratory and circulatory
I gave my students this multiple choice question: Which two body systems would most directly remove extra fluid from a person's lungs?

Only one answer is correct among these 4 choices:
- nervous and digestive
- nervous and circulatory
- respiratory and digestive
- respiratory and circulatory

Could you tell me which one is correct?

respiratory and circulatory