Answer: The homophone that best completes the sentence is "You're".
Explanation: A homophone is a word that is pronounced the same as another word but has a different meaning and, in some cases, a different spelling. For instance, "your" and "you're" are homophones as well as the pair "its" and "it's". However, the homophone that best completes the sentence provided is "you're" (a contraction of the two words "you are") because the speaker is talking to another person. In that way, the use of the pronoun "you" signals the presence of the addressee. In contrast, "your" is a determiner that must be followed by a noun, while "it's" and "its" are used to refer to a thing and not to a person.