One of them will help the poor.

The poor will be helped by one of them

The poor is be helped by one of them

The poor was be helped by one of them

The poor should be helped by one of them

All of the above

The given sentence is in Future Indefinite Tense.

Future Indefinite Tense-Passive Voice

Convert the object of the Active Voice Sentence into the subject of the Passive Voice sentence.

Then use helping verb will be/shall be according to the subject of the Passive Voice Sentence.

Then use the 3rd form of Verb.

After that, use the word “by”, in order to show the doer.