sat-dog

A nonrestrictive clause adds extra information to a sentence, but it's not essential to the meaning of the sentence. It can be removed without affecting the grammatical structure of the sentence. A nonrestrictive clause is set off with commas. In choice A, the nonrestrictive clause is "nestled in the valley" and is correctly set off with commas. Choice B is incorrect because no commas are used to set off the nonrestrictive clause. Choice C is incorrect because the commas are not used to separate a nonrestrictive clause from the rest of the sentence. Choice D is incorrect because the commas are not used to separate a nonrestrictive clause from the rest of the sentence.