Question

Read this example of incorrect sentence structure.

Heavy, black clouds rushing in from the horizon.

Which revision corrects the sentence?

Heavy, black clouds rushing in from the horizon, get under cover.
Heavy, black clouds rushing in from the horizon. It’s about to rain.
Heavy, black clouds rushing in from the horizon when it’s about to rain.
Heavy, black clouds rushing in from the horizon mean a storm is coming.

Answer 1

"Heavy, black clouds rushing in from the horizon mean a storm is coming."

This makes the phrase a complete sentence (subject + verb). The others leave a fragment or create a misplaced/dangling modifier.