Answer:
I can't see the statements so I can't give a definite answer. However, think of it this way: We know the statement needs to add to the idea that insects are dangerous. So you need to chose the option that presents insects in a negative light or gives a specific reason to fear them. A neutral or positive fact about insects would not support the idea.
The subject-verb agreement rule which is being broken in the sentence above is c<span>ollective subjects functioning as a unit require singular verbs.
The collective subject <em>the crew </em>requires a singular verb, because it denotes a single unit. So, instead of using the verb <em>have visited, </em>it should have been <em>has visited. </em></span>
