Answer:
D: Heavy, black clouds rushing in from the horizon mean a storm is coming.
Step-by-step explanation:
The revision in option D corrects the sentence because it presents the part that complements it: the predicate. The phrase "Heavy, black clouds rushig in from the horizon" is the subject , and it is not forming a complete sentence. Now with a verb (mean ), and its complement (a storm is coming ), we have a complete thought, a complete sentence.