Final answer:
Alexander Hamilton advocated for a single executive in Federalist No. 70, emphasizing the advantages of decision-making speed, secrecy, and efficiency, which led to the argument that one person should lead the executive branch.
Step-by-step explanation:
Alexander Hamilton's argument in Federalist No. 70 supports the idea that having a single executive is beneficial due to the decisiveness, efficiency, and capability for swift action associated with a unified leadership. The best summary of Hamilton's viewpoint is that one person should run the executive branch because they can act with decision, activity, secrecy, and dispatch, which are seen as necessary qualities for effective governance. Hamilton believed that a larger group would only serve to dilute these advantages. Thus, the correct answer to the student's question regarding Hamilton's preference for the structure of the executive branch is B: One person should run the executive branch because they will be able to act swiftly, decisively, and discreetly, which is necessary for the presidency.