B is the correct answer. This is a Subject-Verb Agreement problem - we know this because the verb changes among the five answer choices. The subject is the one of every three, and we know that one person is singular. Therefore, the verb also has to be singular. A with the plural live is therefore incorrect. C uses should live, which is a moral imperative, not a fact, and therefore changes the meaning unnecessarily. D employs might live, raising a doubt that again changes the meaning needlessly. And E is incorrect because it uses the past perfect form had lived, which needlessly places the sentence in the past.
"Start By Doing What Is Necessary ,Then What Is Possible & Suddenly You Will Realise That You Are Doing The Impossible"