Question

which body system produces proteins that help fight infections? the digestive system the immune system the muscular system the circulatory system

Explanation:

The immune system is responsible for protecting the body from pathogens. Antibodies, which are proteins, are produced by the immune system to identify and neutralize foreign invaders like bacteria and viruses. The digestive system breaks down food, the muscular system enables movement, and the circulatory system transports blood. None of these produce infection - fighting proteins.

Answer:

the immune system