A$)$ Subject$-$verb agreement:

Correct the subject$-$verb agreement problem in the following sentences, by providing the right verb form, or mark as correct, explaining your correction. Don't change anything but the verb in the sentence. For example:

Sample sentence: You'll work on a document filled with errors that need to be edited and delivered by Wednesday.

Answer: Should read "that needs to be edited" because needs $($verb$)$ pairs with document $($subject$).($The document needs...$).$

One of the main reasons for elephant poaching are the profits received from selling the ivory tusks.

The flags over each building makes them look festive.

What were the reason for so many of his mistakes?

At the $2023$ Grammy Awards, Hip Hop's $50$th anniversary was celebrated with a medley featuring well$-$known rappers from each decade of its history.

She was asked to determine which of the candidates most deserves an award.