Answer:
The answer is A. strengthen
Explanation:
Fad Diets (B) carry the most risk because they usually don't work and a lot of them are making you practically starve yourself and not allow you to get the essential nutrients your body needs.
"Muscles" tense up as a defense mechanism
Lung diffusion is your ability to pass oxygen into the blood from the air sacs of the lungs, and pass carbon dioxide (CO2) back into the lungs from the blood.