The answer is B. You are truly a kind person. The verb "to be" conjugated here as "are" is the correct verb for the pronoun subject of "you". In A. the verb would need to be "have" in stead of "has" to go with the plural you. In C. the sentence makes no sense grammatically because of the syntax and choice of subject. In D. the verb is conjugated incorrectly for the subject of singular self.
