Final answer:
The key group of Department Secretaries known for their significant roles is referred to as the 'inner cabinet,' particularly including the Secretaries of Defense, State, Treasury, and Justice.
Step-by-step explanation:
The small group of more important Department Secretaries within the United States government are sometimes referred to as the inner cabinet. The inner cabinet typically includes the Secretaries of Defense, State, Treasury, and Justice. These department heads are tasked with advising the President on policy areas, implementing policy initiatives, and executing the law. They are the leaders of their respective executive departments, and while the Secretary of each department oversees a massive bureaucratic structure, the ones who are part of this inner cabinet hold more significant roles and receive greater attention from the president, Congress, and the media. A key aspect of selecting these officials is a blend of ability, expertise, influence, and reputation, along with consideration of demographic representation.