The answer should be D. An adjective phrase is a group of words that describe a noun or pronoun in a sentence. The only nouns or pronouns in this sentence are you, jacket, floor, and me. So, if you look at all of these words, only one of them is being described, the jacket. It is being described as being on the floor. So, the adjective phrase would be "on the floor" and the word it modifies, or describes, would be "jacket." Hope this helps!