Step 1: Analyzing the subject.
The subject "He, as well as his friends" is a compound subject. However, the phrase "as well as" does not change the number of the subject, so it remains singular ("He"). Therefore, the verb should agree with the singular subject.
Step 2: Analyzing the options.
- (A) aren't: This is a plural form of the verb, but the subject is singular. Therefore, it is incorrect.
- (B) were: This is a plural past tense verb, but the subject is singular. Hence, it is incorrect.
- (C) was: This is the correct past tense singular form of the verb that agrees with the singular subject "He."
- (D) has: This is a present tense verb, which does not fit with the past action described in the sentence. Thus, it is incorrect.
Step 3: Conclusion.
The correct answer is (C) was, as it agrees with the singular subject "He."