Answer :
I believe that the answer is D. Because The clouds in the sky this morning isn't a complete sentence. A sentence has to have a subject and a predicate, the predicate is what the subject (person, place, or thing) is doing. Subject: clouds
(a thing), Predicate (unknown there is no verb or statement saying what they are doing)
(a thing), Predicate (unknown there is no verb or statement saying what they are doing)