Which department’s responsibilities include managing the country's national parks?

The responsibilities of managing the country's national parks fall under the Department of the Interior. This department is primarily tasked with the stewardship of federal land and natural resources, which includes overseeing national parks and monuments, wildlife refuges, and other conservation areas. The National Park Service, a bureau within the Department of the Interior, is specifically responsible for managing national parks and ensuring their preservation and protection for future generations while also providing opportunities for public enjoyment and education.

The other departments mentioned have distinct roles that do not encompass the management of national parks. The Department of Defense focuses on national security and military matters, the Department of Commerce deals with economic growth and trade, and the Department of Energy manages the country’s energy policies and nuclear material. Thus, the Department of the Interior is uniquely positioned to handle matters related to national parks and environmental conservation.