Final answer:
Shared power in a federal system includes raising and supporting armed forces, a responsibility shared between federal and state governments, with states maintaining National Guard units for both state and federal use.
Step-by-step explanation:
The concept of shared power in a federal system of government pertains to powers that are both separate and shared between the federal and state governments. When we consider the options provided, we can see that raising and supporting armed forces is a shared power between the federal and state governments. States rely on the federal government for the nation’s defense, but they also maintain their own National Guard units which can be mobilized for state or federal purposes, reflecting a partnership in militaristic responsibilities.
On the other hand, states have a more direct role in licensing professional workers, controlling foreign trade falls under federal jurisdiction, and providing healthcare and welfare is predominantly a state concern with significant federal involvement and regulation.