What is this? Please answer with an explanation

It's C.

Explanation:

The process of nitrification is that is a process that converts ammonia to nitrite and nitrite to nitrate. It is an important step in the global nitrogen cycle. It is exclusively carried out by prokaryotes, which is a group of organisms called bacteria.

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i can't see the full page, therefore, can't answer it

explanation:

the answer is b.) hydrogen bonds between bases.