Answer:
The sentence from this passage that explains what the main characters do in Rosencrantz and Guildenstern Are Dead is "As in Beckett's play, Rosencrantz and Guildenstern pass the time by impersonating other characters, engaging in word play, and remaining silent for long periods of time."
Explanation:
Tom Stoppard's play, Rosencrantz and Guildenstern Are Dead, take this two characters from Hamlet's childhood that have been used in several plays before, here is a description of their activities which are not different from the activities they had in previous works, it is not mentioned what activities from Hamlet do they do, just from Beckett's play.