Sometimes States Legislate on the Same Subject as Congress

Sometimes states legislate on the same subject as Congress. If Congress passes a regulation:

A) states must abolish their regulations because state law cannot exist along with Federal law
B) federal regulation takes precedence over state laws that conflicts with the federal standards
C) state law has more power within the state as long as relevant actions occur in the state
D) the states are able to reduce the impact of the federal law by adding their own law to it
E) none of the other choices are correct