Which sentence is NOT a correct passive voice transformation of its active counterpart?

Correct option is C

The correct option is (c).

Option (c) is NOT a correct passive transformation because the passive sentence given as Sung by her is incomplete and does not follow the correct passive structure. A correct passive transformation must have a subject (object of active), an appropriate form of be, and the past participle (V3).

Step-by-step reasoning:

• Active sentence: She sings a song.
• Object of the active sentence: a song.
• In passive, the object becomes the subject: A song becomes the subject.
• Since the tense is simple present (sings), passive uses: is/am/are + V3.
• Correct passive should be: A song is sung by her.

Rule and structure:

• Active: Subject + V1/V2 + Object
• Passive (Simple Present): Object + is/am/are + V3 + by + Subject

Why other options are correct transformations:

• (a) We eat the cake → The cake is eaten by us (simple present passive structure is correct).
• (b) He gives her a gift can become A gift is given to her by him (one of the correct passive forms for double-object verbs).
• (d) They open the door → The door is opened by them (correct).

Information booster: In exams, incomplete passive forms without a clear subject and auxiliary verb are treated as incorrect even if the V3 is present.

So the correct answer is (c)