Select the option that expresses the given sentence in passive voice.

Pay the electricity bill for the month of April.

Let the electricity bill for the month of April be paid.

The correct passive voice of the given sentence is The electricity bill for the month of April must be paid.

The active voice of the sentence is Pay the electricity bill for the month of April. This sentence is in the imperative mood, which is used to give commands or make requests. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "the electricity bill for the month of April" and the main verb is "pay." The past participle of "pay" is "paid." So, the passive form of the sentence is The electricity bill for the month of April must be paid.

The other options are incorrect because:

• The electricity bill for the month of April has to be paid. is grammatically correct, but it is not as concise as the other options.
• We should pay the electricity bill for the month of April. is in the active voice, but the subject of the sentence is "we." This is not correct because the person who is paying the bill is not "we."
• Let us pay the electricity bill for the month of April. is in the imperative mood, just like the original sentence.
• Let the electricity bill for the month of April be paid. is the most concise and correct passive voice of the sentence.