Final answer:
The main responsibility of the federal executive bureaucracy is to enforce federal laws/rules, (option b) aligned with the President's Constitutional duty to ensure that the nation's laws are properly implemented.
Step-by-step explanation:
The major responsibility of the federal executive bureaucracy is to enforce federal laws/rules. This role is primarily executed through the Office of the President of the United States, which is charged with ensuring that the laws passed by Congress are implemented and observed throughout the country. The President oversees this process by appointing heads to the cabinet departments and various executive agencies, like the CIA and EPA, with these appointments subject to Senate confirmation. Additionally, the President has the power to issue executive orders to interpret and carry out legislation, and supervises other officers of the executive branch to ensure lawful procedures.
The vast federal executive bureaucracy has grown significantly since the 1930s and today consists of more than 60 agencies, over 2,000 bureaus, and employs more than two million civilian workers across the globe. These entities work under the executive branch to administer and regulate federal policies and programs in line with the laws enacted by Congress. Hence, the bureaucracy's primary function aligns with the Constitutionally endowed responsibility of the President to take care that the laws be faithfully executed.