Question:

The fact that they have been awarded so many prizes ________, even more, their many years of hard work for the local community.
Which of the following options correctly completes the sentence above?

A highlights

Explaination

A subject must agree with its verb in number. The subject in this sentence (the fact that…) is singular, so we need a singular verb (highlights).
The use of “highlighting” does not make sense in this sentence without the presence of a helping verb (is higlighting could be correct).
The use of the verb “highlight” would require a plural subject.
The use of the verb “have highlighted” would require a plural subject.