at the tissue level at the organ level at the system level at the cellular level
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: When athletes begin to exercise, their heart rates and respiration rates increase. At what level of organization does the human body coordinate these functions?
Possibilities:
- at the tissue level
- at the organ level
- at the system level
- at the cellular level

at the system level