to digest food to help in defense to eliminate waste to enable movement
I gave my students this multiple choice question: The human body is composed of different systems made of specialized cells, tissues, and organs. Each of these structures has a specific function that aids in the survival of the human species. What is the primary function of the excretory system?

Only one answer is correct among these 4 choices:
- to digest food
- to help in defense
- to eliminate waste
- to enable movement

Could you tell me which one is correct?

to eliminate waste