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

You must observe silence in the library.

Silence must be observed by you in the library.

The correct Active/Passive form of the given sentence is Silence must be observed by you in the library.

The original sentence is in the Active voice, with the subject "you" performing the action of "observing" silence in the library. The passive voice of the sentence would have silence as the subject, and the action of "being observed" would be performed on it. The correct passive voice form of the sentence would be Silence must be observed by you in the library.

The other options are incorrect. The library must be observed silence by you is grammatically incorrect because the verb "observed" is in the past participle form, but the subject of the sentence is the library, which is not an action.

Silence might be observed by you in the library is grammatically incorrect because the modal verb "might" is used to express possibility. The sentence does not indicate that silence might be observed in the library.

Silence in the library must have been observed by you is grammatically correct, but it is not as concise or natural as the active voice form of the sentence.