The boy laughed at the beggar.

This question is based on the transformation of a sentence from Active Voice to Passive Voice, which is a common topic in competitive English.

Voice: In grammar, voice refers to the form of a verb that indicates whether the subject performs the action (active voice) or receives the action (passive voice).

Active Voice Structure: Subject + Verb + Object
Passive Voice Structure: Object + appropriate form of "to be" + past participle (V3) + by + Subject

Original Sentence (Active Voice): The boy laughed at the beggar.

Step-by-step Breakdown:
1. The object "the beggar" becomes the subject in the passive sentence.
2. The verb phrase is "laughed at", which is a phrasal verb. In passive voice, the entire phrase must be preserved.
3. The correct tense is simple past, so the passive form uses "was" + past participle ("laughed").
4. Maintain the preposition "at" with the verb.
5. The subject "the boy" comes after "by".

Correct Transformation:
The beggar was laughed at by the boy.

Correct Answer: Option D: The beggar was laughed at by the boy.

Other Options:
Option A: The beggar was laughed by the boy. — ❌ Incorrect. Omits the necessary preposition "at", making it grammatically incorrect.
Option B: The beggar was being laughed by the boy. — ❌ Incorrect. Incorrect tense ("was being" indicates past continuous) and missing "at".
Option C: The beggar was being laughed at by the boy. — ❌ Incorrect. Wrong tense; this changes simple past into past continuous.

Conclusion: The sentence that correctly follows the passive voice structure while preserving the meaning and tense is Option D.