The supremacy clause forms the roots of what aspect of the country government system

The Supremacy clause forms the root of the aspect of "federalism" within the country's government system.  Although power is shared between the federal government reigns supreme.

Explanation:

the secretary of defense is the principal defense policy advisor to the president. under the direction of the president, the secretary exercises authority, direction, and control over the department of defense.

as you did not provide any choices for me to choose from to give you a direct answer, this is the only information i can provide.