The correct answer is: A. He was laughed at by all his friends.
The sentence “All his friends laughed at him” is in the passive voice. In the passive voice, the subject of the sentence is acted upon by the verb. In this case, the subject is “he” and the verb is “laughed at.” The passive voice is often used to focus on the action rather than the person or thing doing the action. In this case, the focus is on the fact that “he” was laughed at, not on who did the laughing.
The other options are all in the active voice. In the active voice, the subject of the sentence is doing the action. In these cases, the subjects are “he” (option B), “all his friends” (option C), and “all his friends” (option D). The active voice is often used to focus on the person or thing doing the action. In these cases, the focus is on the fact that “he” laughed (option B), “all his friends” laughed (option C), and “all his friends” were laughing (option D).
However, in the context of the sentence “All his friends laughed at him,” the passive voice is more appropriate. This is because the focus of the sentence is on the fact that “he” was laughed at, not on who did the laughing.