What to stephano and trinculo do when they hear mysterious music on the island?
a. they hide in the nearby bushes
b. they fear for their lives
c. they draw their swords
d. they beg caliban for protection

B. They fear for their lives.

In Act III, scene ii, we see Stephano, Trinculo and Caliban plotting against Prospero. Caliban hates Prospero and desires to be free, therefore, he is ready to join Stephano in his plans to take over the island and marry Miranda. As the group talks, they drink, and the scene is comical as they begin to get more and more intoxicated. Ariel appears, and he is not happy with the scene. After interferring verbally, he plays music. Upon hearing the music, the men, who cannot see Ariel or the source of the music, become very fearful.

the underline word is basically like a prepositional phrase.