The answer is B: The clause "who as born in Virginia" needs to be set off by commas because it is a nonrestrictive element. This clause is nonrestrictive element because it adds further information about Thomas Jefferson, but it is not essencial to the meaning of the sentence, which means that if it is excluded, the readers will still understand the general meaning of the sentence. It uses commas to separate the additional information. Commas are always used when the word modified by the appositive is a proper noun.