Choose the option that is the correct passive form of the sentence.

She ate the last slice of pizza.

The last slice of pizza was eaten by her.

The correct passive form of the sentence "She ate the last slice of pizza" is The last slice of pizza was eaten by her.

The active voice of the sentence is "She ate the last slice of pizza." This sentence is in the simple past tense, which is used to describe an action that happened in the past. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "last slice of pizza" and the main verb is "eat." The past participle of "eat" is "eaten." So, the passive form of the sentence is The last slice of pizza was eaten by her.

The other options are incorrect because:

• She had eaten the last slice of pizza. is in the past perfect tense, which is used to describe an action that happened in the past before another action happened. There is no other action mentioned in the sentence, so the past perfect tense is not appropriate.
• The last slice of pizza had been eaten by her. is also in the past perfect tense.
• The last slice of pizza was being eaten by her. is in the present progressive tense, which is used to describe an action that is happening now but is not finished. The sentence is describing an action that happened in the past, so the present progressive tense is not appropriate.
• The last slice was being eaten by her. is missing the subject of the sentence. The subject of the sentence is "the last slice of pizza."