They were totally unaware of the impending disaster.

A. threatening

B. imminent

C. terrible

D. possible

Answer: Option B

Solution(By Examveda Team)

threatening : having a hostile or deliberately frightening quality or manner.
imminent : about to happen.
terrible : extremely bad or serious.
possible : able to be done or achieved.
impending : be about to happen.


Synonym of impending is imminent