Answer:
Are there any answer choices?
I would say:
The past passed very quickly.
I believe that the best answer for this question is an adjectival prepositional phrase because it describes a noun. It modifies the words "a pygmy hippo," which is the subject of the sentence and therefore a noun. Adjectival prepositional phrases modify nouns, while adverbial prepositional phrases modify verbs, adverbs, or adjectives. Hope this helps.
