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.
Sweet laughter in mirthfulness artlessly flowing.
Laughter and tears are meant to turn the same machinery of sensibility.
Laughter rich as woodland thunder.
Laughter like a chime of bells.
Sweet laughter in mirthfulness artlessly flowing.
Answer:
We knew it was time to evacuate when the water was steadily pouring through broken windows. The water reached three feet deep.