Which sentence has a noun clause used as its subject? a) my watch was really expensive, but it was also really easy to break. b) glenn regretted that she had never spent time learning to play the guitar. c) mr. morrissey does not like to eat almonds in any form--even if covered in chocolate. d) a car that has been sold five times in the last year is probably not the best car to buy.

D) A car that has been sold five times in the last year is probably not the best car to buy.

Explanation:

A noun clause is a dependent clause (a group of words containing a subject and a verb and that can not stand on its own) that acts as a noun in a sentence, it can function as a subject, a direct or indirect object, a predicate nominative, or an object of a preposition.

When it acts as a subject, the clause is the thing, person or event that is being discussed, described, or dealt within the sentence. In option D, "A car that has been sold five times in the last year" is the noun clause that is used as a subject because it is the noun that is being dealt with, all the rest of the sentence is the predicate.