An individual was exposed to a contagious disease but did not become infected. the agent was unable to enter the body and grow because it was stopped by the person's skin. this is an example of how a can prevent disease. a. chemical barrier b. physical barrier c. protective behavior d. medication

Answer;

B. physical barrier

Explanation;

Natural barriers and the immune system defend the body against organisms that can cause infection. Natural barriers include the skin, mucous membranes, tears, earwax, mucus, and stomach acid.

Physical defenses provide the body's most basic form of nonspecific defense. They include physical barriers to microbes, such as the skin and mucous membranes, as well as mechanical defenses that physically remove microbes and debris from areas of the body where they might cause harm or infection.

what effect does exercise have on the nervous system?

the answer is c.