Rahul and his friends . . . . . . . . also invited to the party. A. is B. was C. had D. were

The correct answer is: D. were

The verb “to be” is conjugated in the past tense when the subject is plural and refers to a specific time in the past. In this case, the subject is “Rahul and his friends” and the time is when they were invited to the party. Therefore, the correct verb form is “were”.

The other options are incorrect because they do not agree with the subject or the time reference. Option A, “is”, is in the present tense, which does not agree with the past tense time reference. Option B, “was”, is in the singular form, which does not agree with the plural subject. Option C, “had”, is in the past participle form, which is not used as the main verb of a sentence.