Which powers are solely at the state level?
expressed
implied
concurrent
reserved

 reserved powers are solely at the state level.

Explanation:
In the Tenth change, the Constitution conjointly acknowledges the powers of the state governments. historically, these enclosed “police powers” of health, education, and welfare. such a large amount of states feared the expanded powers of the new national government that they insisted on amendments throughout the Constitution's approval.
reserved powers are the powers that don't seem to be "enumerated" Reserved powers also are distinguished from completely delegated powers

The answer to the question is a.