In order for a physical barrier to be effective in preventing infection, the barrier must

In order for a physical barrier to be effective in preventing infection, the barrier must be able to prevent a pathogen from entering the body, trap the pathogen when it first enters the body or flush it out of the body. Physical barriers of the body include the skin, mucous membranes, earwax, tears, mucus and stomach acid. The normal flow of urine also washes out microorganisms that try to enter the urinary tract. When the bladder empties, it flushes out any bacteria that may be attempting to reach it

Ibelieve the answers are a and c.

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.