A prepositional phrase has to start with a preposition, and the only option here which starts with one is D, 'during the darkest night', where 'during' is a preposition.
the poem above is a sonnet
The girls, Joanna and Mary Jane, have treated Huck very nicely, which is the reason why he decides to steal the gold back from the Duke and the King and give it back to them. He didn't want to swindle those kind girls any longer, which is why he wanted to help them rather than conceal those two criminals.
