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.
Hey There!!
Your best answer choice will be is Were.
Because You were the most important person at the time makes sense. But, If you put You was the important person at the time doesn't make sense at all... Hope This Helps!!
By ♡~Itsbrazts♡~
