circulatory system excretory system immune system nervous system
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: The digestive system breaks food down into molecules that are used by our body's cells. Which other body system regulates how fast or slow the digestive system functions?
Possibilities:
- circulatory system
- excretory system
- immune system
- nervous system

nervous system