During the late 19th century, presidents were subordinate to:

The correct choice indicates that during the late 19th century, presidents operated under the influence and authority of the Senate Foreign Relations Committee, particularly in matters related to foreign policy and treaties. This period was characterized by a political culture where congressional power was particularly strong, which often meant that presidents had to navigate the legislative process carefully, especially when seeking approval for international agreements and foreign engagements.

The Senate Foreign Relations Committee played a crucial role in advising on foreign policy and was integral to treaty negotiations. Presidents needed the Senate's consent to ratify treaties, frequently leading to a relationship where the committee's preferences and political dynamics shaped presidential actions and strategies. As such, the president's ability to independently conduct foreign policy was often limited by the need for congressional support, marking a period where congressional authority, particularly in foreign relations, was substantial.