Answer:
D) Dark, billowing clouds often are signs of a bad storm on the way.
Step-by-step explanation:
The present particle refers to an adjective which derives from a verb and contains the ending -ing. As a result, the adjective billowing, which means filled with air and distended outward, is in the present participle form.
The rest of the options are incorrect because the -ing forms are gerunds and gerund phrases, which function as nouns and objects, not adjectives.