Post the sentence.. how else are we gonna know
<span>Marilyn is a good person in this story, because all she wanted to do was see her brother. so she went on board of a medicine ship. the ship that Marilyn when on board of, cant hold anymore weight then the amount that it has already. So if the captain wants to live, and deliver the medicine to the planet, then he is going to have to throw her off board. Marilyn does not know that though, she thinks that she will only get fined.</span>
A prepositional phrase contains a preposition and usually a noun. Your answer would be the first choice.
example:
I went over the hill. "Over the hill" is a prepositional phrase.
