From the given alternatives, choose the one which best expresses the sentence in Active/Passive voice.
A child could not have done this misconduct

This misconduct could not have been done by a child.

The correct answer is This misconduct could not have been done by a child.

The original sentence is in active voice, with the subject "child" and the verb "could not have done". To change it to passive voice, we make the object of the active sentence, "misconduct", the subject of the passive sentence. The verb "could not have done" becomes "could not have been done", and we add the preposition "by" to show who is doing the action. This gives us the passive voice sentence "This misconduct could not have been done by a child".

The other options are incorrect.

• This misconduct could not been done by a child is grammatically incorrect. The past participle "been" should not be used with the modal verb "could".
• This misconduct a child could not have been done' is not a complete sentence. It does not have a subject or a verb.