Final answer:
After the king, queen, Polonius, and Ophelia enter, Hamlet's behavior changes, becoming more focused and direct.
Step-by-step explanation:
After the king, queen, Polonius, and Ophelia have entered, there is a change in Hamlet's behavior. Previously, Hamlet was clouded and seemed agitated. However, upon their entrance, Hamlet becomes more focused and direct, asking Polonius and Horatio for information and guidance. This change in Hamlet's demeanor suggests that he sees an opportunity to gather information or make progress in his plans.