Question

the ____ system protects the body against invaders.
options: immune, respiratory, circulatory, digestive (each with a radio button)

Explanation:

The immune system's main function is to defend the body against foreign invaders like bacteria, viruses, and other pathogens. The respiratory system is for gas exchange, the circulatory system transports blood and nutrients, and the digestive system processes food. So the correct option is the one related to defense against invaders.

Answer:

A. immune