Answer:
D. Must.
Step-by-step explanation:
The sentence “Everyone has umbrellas up” indicates present tense, saying that it is raining right now. Options A, B, and C are all past or future tense, so they are incorrect.
The correct answer is D because it is the only option that fits the tense of the original sentence, and it makes sense when inserted into the sentence.
It will be raining. Everyone has umbrellas up.