Select the correct passive form of the given sentence.
She held the child’s hand firmly.

Correct option is D

The correct passive form of "She held the child’s hand firmly" is "The child’s hand was held firmly." This maintains the past tense and the firmness of the action.
Conversion rule:
Subject + V2 + object. -> <- Object + auxiliary verb (was, were) + past participle + by + subject.
Other options are incorrect because:
• "is held" – present tense.
• "has been held" – present perfect tense.
• Lacks a verb to be.