- Excretion is when the excretory system removes waste from the body
- The excretory system performs excretion
- So, the excretory system removes waste from the body

- The excretory system removes waste from the body
- Removing waste is a kind of function
- Hence, removing waste from the body is a function of the excretory system

Therefore, removing waste from the body is a function of the excretory system
Removing waste from the body is the primary function of which body system?
- Excretion is when the excretory system removes waste from the body 
- The excretory system performs excretion 
- Removing waste is a kind of function