Change the sentence into passive voice: All his friends laughed at him.

The correct answer is D. The original sentence is in the simple past tense. Its subject, "All his friends", performs the action "laughed at" on the object "him". In passive voice, the object becomes the subject, the verb changes to the past passive form (was/were + past participle), and the original subject moves after "by". Since "he" is singular, "was" is used, and "laughed at" keeps its preposition because it is a phrasal verb. The result is "He was laughed at by all his friends."

• A simply swaps the subject and object while keeping the active voice, so it is not a passive transformation.
• B shifts the sentence to the present tense, changing both the tense and the meaning.
• C uses "is", the present passive, but the original sentence is in the past tense. Tense must be preserved during conversion.

Core concept: tense-preserving conversion from active to passive, including phrasal verbs like "laugh at" where the preposition stays attached to the verb. This is a standard pattern in the English section of UPPSC Prelims, and it supports the clear, precise sentence construction you need for the Mains language and essay papers.

Trap: Picking C because "is laughed at" looks like a neat passive, without first checking the tense of the original sentence.