I believe A is the most correct (i assume it's about antibiotics - they actually DO harm our immune system in some way).
B is partially correct because, the colds indeed should be treated by anti-viral medication (because the virus is a cause of typical cold) but using antibiotics during recovery is needed only when an additional bacterial infection occurs as a complication after the viral infection. and it doesn't happen very often.
C - what works? antibiotics doesn't work for viral infections (colds). anti-viral medication do.
D i won't discuss.
I am sorry for a so long answer. but your question is so linguistically twisted that i am not sure which of the following choices is actually correct because of a big amount of mistakes.
First, we can eliminate 2 options. The simple unit of protein is amino acid, instead, the simple unit of fat and lipids are fatty acids and glycerol, therfore we can eliminate option A and D because fatty acids does not exist in protein.
Now we are left with B and C. To solve that, we need to understand that protein is made of a chain of amino acids, a lot of amino acids are chemically combined and cannot be broken down unless the use of enzymes. Amino acid are actually the monomers that forms protein.
Therefore, the answer is C. amino acid combine to form a protein chain.
Anther, stigma, and style are male reproductive structures in flowers.
The ovary is a female reproductive structure
Answer:
a. 8.1 milligrams
b. 40.07 hours
c. 8.859 milligrams
Explanation:
If a person takes a prescribed dose of 10 milligrams of Valium, the amount of Valium in that person's bloodstream at any time can be modeled by

Where A(t) = amount of Valium remaining in the blood after t hours
t = time or duration after the drug is taken
a. we have to calculate the amount of drug remaining in the bloodstream after 12 hours


= 10×0.81253
= 8.1 milligrams
b. In this part we have to calculate the time when A(t) = 5 milligrams


0.5 = 
Now we take natural log on both the sides of the equation.
ln(0.5) = ln(
-0.69314 = -0.0173t
t = 
t = 40.0658
≈ 40.07 hours
c. In this part we have to calculate the rate, by which amount of drug will decay in the bloodstream after 7 hours.


= 10×0.8859
= 8.859 milligrams