The correct answer is A. All flags were flying.
Explanation
A complete phrase is composed of a subject, a verb, and a compliment that also expresses a completely coherent idea. According to this definition, the correct answer is A. because it has a subject "All flags", a verb "were" and a complement "flying". Also, it expresses a complete and coherent idea.
I think the answer is c i hope this helps you out
"All of a sudden..." is a transition that shows suspense. It says something happened, but it didn't happen with any warning and it doesn't tell the reader up front what went on or if it was good or bad.
