Which of the following was a responsibility of Thomas Jefferson as President?

Thomas Jefferson, as President of the United States, had the responsibility of signing treaties, which is a key function of the executive branch under the Constitution. This authority is derived from Article II, Section 2, which states that the President has the power to negotiate and sign treaties with foreign nations, provided that these treaties receive advice and consent from the Senate. Signing treaties is a critical aspect of foreign policy and national diplomacy, allowing the President to engage with other countries, establish alliances, and negotiate important agreements that can affect the nation's interests.

The other responsibilities listed—leading military operations, drafting the Constitution, and establishing the judiciary—are not roles that Jefferson held during his presidency. While Jefferson was involved in military decisions, the actual command of the military was more closely related to his role as a leader rather than an operational command. Drafting the Constitution was the work of the Constitutional Convention, which occurred before Jefferson's presidency. Similarly, establishing the judiciary was the responsibility of the legislative branch and was formalized even before Jefferson assumed office. Thus, the responsibility of signing treaties distinctly aligns with Jefferson's presidential duties.