The power to declare war is: a-given to the states if the national government falls
b-given both to states and the national government
c-granted only to the individual state governments
d-granted to the national government, not states
in Article 1, Section 8. This power is not shared with anyone, including the President. The President, however, is just as clearly made the Commander in Chief of all of the armed forces. So I would go with D.