Which body system produces proteins that fight infections
the digestive system
the immune system
the muscular system
the circulatory system

Ans.

The body system that functions to fight infections and provides immunity to the body is immune system. Various protein molecules are synthesized and released by immune system that fight with disease-causing pathogens. An example of immune proteins is antibodies, which are responsible for identification and neutralization of foreign pathogens.

Thus, the correct answer is 'option). the immune system.'

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck