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.
<span>If you look at hominids' mouths you can learn a lot. You can compare the teeth to see what they eat. Different foods cause a different amount and type of wear. You can also point out individuals by matching their teeth with what you know about them.</span>
<span>They are clones of the parent plant.!</span>
