Thomas jefferson who was born in virginia wrote the declaration of independence. the clause “who was born in virginia” needs to be set off by commas because it is a restrictive element. the clause “who was born in virginia” needs to be set off by commas because it is a nonrestrictive element. the sentence is correct as written.

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.

when parallel rays of light pass through a concave lens, the refracted rays diverge so that they appear to come from one point called the principal focus.