To determine the most appropriate verb for the sentence "One of my friends is going to (part B)," we need to consider the subject of the sentence. In this case, the subject is "one," which is singular. Therefore, the verb should also be singular to agree with the subject. The correct form of the verb in the context of this sentence is "is," making the correct sentence: "One of my friends is going to (part B)."
"Is" is the correct singular form used to accompany "one."
"Are" and "were" are plural forms and do not match the singular subject.
"Was" is singular but is in the past tense and does not match the present context of the action.