Select the correct Active/Passive form of the given sentence.

My book had been stolen yesterday.

Someone had stolen my book yesterday.

The correct Active/Passive form of the given sentence is Someone had stolen my book yesterday.

The sentence is in the Passive voice, with the subject "my book" having something done to it by someone or something. The action of "being stolen" is performed on the book by an unknown person. The correct passive voice form of the sentence would be "Someone had stolen my book yesterday."

The other options are incorrect. Yesterday he stole my book is in the Active voice, but the verb tense is incorrect. The verb "stole" is used in the past tense, but the sentence indicates that the action of stealing the book happened before yesterday. The correct verb tense for the active voice of this sentence would be "had stolen."

He stole my book yesterday is also in the Active voice, but the subject of the sentence is not the unknown person who stole the book. The subject of the sentence is the person who is speaking, and the action of "stealing" is performed on the book by the speaker. This is not grammatically correct, as the speaker is not the one who stole the book.

Someone has stolen my book yesterday is also in the Passive voice, but the verb tense is incorrect. The verb "has stolen" is used to indicate that the action of stealing the book happened in the past and continues to have an effect in the present. However, the sentence does not indicate that the book is still missing.