Answer:
C.
Explanation:
So, a pathogen is something that causes disease, like a virus like the rhinovirus, which causes the common cold.
It is a perfect example of a natural selection.
(I'm not sure if this is the exact answer that you are looking for.)
If i remember correctly they should be adenine (A), thymine (T), guanine (G) and cytosine (C). i hope this helps. sorry if they arent all correct.
