In a Federal System of Government What Is the Role

In a federal system of government what is the role of the national government when disputes arise between states?

A) The federal government is powerless in disagreements between states.
B) The federal government has legislative powers to arbitrate disagreements between states.
C) Disagreements between states are arbitrated by a council of state executives; the federal government has no role.
D) The federal government has an equal vote and stake, as do the two or more states that are disagreeing.
E) The high courts of the states in disagreement arbitrate the dispute without interference of the federal government.