The correct passive voice form of the sentence "Could you pass the test?" is: (3) Could the test be passed?

 sentence "Could you pass the test?" is in the active voice, where "you" is the subject, and "pass" is the verb. To change this into the passive voice, we need to make the object of the active voice sentence (in this case, "the test") the subject of the passive voice sentence and then use the appropriate form of the verb "to be" followed by the past participle of the verb "pass."

So, "Could the test be passed?" is the correct passive voice form. It maintains the same meaning as the active voice sentence but shifts the focus from the doer of the action (you) to the receiver of the action (the test).