Conjugation. I hope this helps!
Because our bodies work to fight off unknown substances like bacteria
The answer is C. My explanation is that in the sentence, it has the words “will probably,” next to each other, so that means it is not a fact and it is not a 100% for certain that it will/had happen(ed). People may have different feelings/views about it. Also, all of the other sentences are more direct and do not have those words, and they sounds confident. Hope this helps!
It's option D because both are depending upon each other (interdepending) for their needs.
