An Instructor Explains Factors That Can Influence the Body's Ability

An instructor explains factors that can influence the body's ability to defend itself against infection. A student shows a need for additional instruction by saying:

A) "In elderly individuals, the immune system gradually decreases in effectiveness, leaving them more vulnerable to invading pathogens."
B) "Toxicity from chemicals can impair the body's ability to fight infection."
C) "A diet that is lacking in fruits and vegetables can negatively affect the body's defenses."
D) "Mucous membranes can provide a portal for microorganisms to bypass the body's defenses and enter the body."