From the given alternatives, choose the one which best expresses the sentence in Active/Passive voice.
Who is creating this problem?

By whom is this problem being created?

The correct answer is By whom is this problem being created?

The original sentence is in active voice, with the subject "who" and the verb "creating". To change it to passive voice, we make the object of the active sentence, "problem", the subject of the passive sentence. The verb "creating" becomes "is being created", and we add the preposition "by" to show who is doing the action. This gives us the passive voice sentence "By whom is this problem being created?".

The other options are incorrect.

• Who has been created this problem? is in the passive voice, but it is not grammatically correct. The verb "created" should be "being created".
• Who created this problem? is in active voice, but it does not ask who is creating the problem. It asks who created the problem in the past.
• By whom has this problem been created? is in passive voice, but it is not grammatically correct. The preposition "has" should be "is".
• By whom this problem is being created? is not in passive voice. The subject of the sentence is "By whom", which is not a person. This sentence is not grammatically correct.