Active-to-passive voice (prepositional verb): Convert the sentence to passive, retaining the preposition with the verb. Source sentence: She spoke to the official on duty. Instruction: Choose the grammatically correct passive-voice option.

Given data

• Verb pattern: speak to someone (prepositional verb).
• Active: She spoke to the official on duty.

Concept / Approach
In passive, the preposition to remains with spoken (spoken to). The object of the preposition becomes the subject.

Step-by-step transformation
Object of preposition → subject: the official on duty → The official on dutyAuxiliary in past: wasPast participle + preposition: spoken toAgent: by herFinal passive: The official on duty was spoken to by her.

Eliminate wrong options
A: Correct passive with preposition stranded after the verb. ✅B: Misplaced on duty modifying her; changes meaning. ❌C: Swaps roles; wrong subject. ❌D: Unrelated infinitival construction; incorrect. ❌

Final Answer
The official on duty was spoken to by her