The correct answer is A.
A subject-verb agreement implies that the subject of the sentence and the verb of the sentence must be in agreement in number.
A pick and shovel ( two things, therefore plural ) <em>are used</em> to remove sand;
When two subjects are joined by <em>and</em>, the verb is plural.
then workers or a crane <em>lifts</em> the artifacts.
When two or more singular nouns or pronouns are connected by <em>or </em>or <em>nor</em>, a singular verb is used. The verb agrees in person and number with the noun nearest to it.
The sentence that sounds the best when you read it out loud is:
C. Summer vacation came as a relief to the student, who was tired of studying and writing research papers.
If you read all the sentences out loud they all sound weird except for this one.
I believe that the answer is A and C, but if i had to choose it would have to be A
