integumentary and circulatory systems digestive and reproductive systems endocrine and respiratory systems digestive and immune systems
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which two body systems interact to produce antibodies that require essential amino acids?
Possibilities:
- integumentary and circulatory systems
- digestive and reproductive systems
- endocrine and respiratory systems
- digestive and immune systems

digestive and immune systems