Answer:
The correct answer is A. prepositional phrase.
Explanation:
The word against is a preposition, and with the words that follow it, it makes a prepositional phrase.
A verbal phrase would contain a verbal (gerund or participle).
An appositive phrase would be surrounded by commas.
An absolute phrase modifies a noun and can be omitted from the sentence without changing its meaning (here, against the sky cannot be omitted).
