I believe the supernatural
The complete predicate in this sentence is A. mopped his brow, exhaled sharply, and picked up his phone.
B and C aren't correct, because they aren't complete predicates - something is missing.
D isn't correct, because <em>looking up from his computer monitor </em>is not a predicate, it is an adverb phrase.
<span>Prince Escalus is the answer</span>
Great story! If you're still continuing on the story, I suggest adding a falling action for the conflict.