Final answer:
The correct answer is 'go,' as the verb must agree with the closest subject, 'brothers,' which is plural. Either Jeff or his brothers go to Miami for Spring Break every year.
Step-by-step explanation:
The question deals with subject-verb agreement in English grammar. In the sentence 'Either Jeff or his brothers go to Miami for Spring Break every year,' we use the verb that agrees with the noun closest to it, which in this case is 'brothers.' Since 'brothers' is a plural noun, the correct verb to use is 'go.'
Understanding Subject-Verb Agreement
In English, it's important that the verb correctly agrees in number with the subject of the sentence. When presented with compound subjects connected by 'or' or 'nor,' the verb should agree with the part of the subject nearer to the verb. This rule helps us decide between singular or plural verbs.