<em>rulers gained power by surrounding themselves with loyal officers</em>. This is the right answer.
In this excerpt , Hamlet shows Rosencrantz is <em>too loyal</em> to Claudius. In fact, Hamlet thinks he is Claudius' spy. Hamlet has jut killed Polonius and Rosencrantz asks him about Polonius' body. Hamlet calls Rosencratz a sponge because he does what the king orders and in this way the king becomes so powerful. The king uses their loyal men but then , he will also get rid of them. Hamlet does not tell Rosencratz where the body is.
These options are not right:
-sponges were new and popular in Elizabethan society. ( The sponge is used as a metaphor. The king makes his loyal men<em> soak</em> his needs).
-scientists in the 1600s were studying the human body. ( The metaphorical use of the sponge is not related to science).
-common people felt that they were ignored by their royal leaders ( The focus is put on men loyal to the king, Rosencrantz, not on common people).