Correct Answer: (c) his friends, were
Solution:According to the 'Subject-Verb Agreement rule', "Subject(1st) + as well as/ with/ along with/ together with/ + Subject(2nd) + Verb" is grammatically the correct structure. However, the verb should be used according to the first subject. In the given question, the 1st subject (The boy) is in the singular form so it will use 'was' as a singular verb. Hence, 'his friends, was' will be the most appropriate answer.