<span>Choice (D) is the most grammatically correct sentence. This sentence has a dependent clause followed by an independent clause, both separated by a comma. This allows for the two clauses to be properly joined and for the sentence to contain a logical flow.</span>
<span>two or more independent clauses and one or more subordinate clauses</span>
Nimbostratus is the type of cloud.
Although there are no conjunctions in this sentence, I guess that the adverb where can be used as a "subordinating conjunction" in the sentence, because it connects the subordinate and the independent clauses.
A stray dog roamed aimlessly through the neighborhood last night.Hope i helped
:D