Question

why was it threatening to the united states that one or more of the states could declare that they would disregard federal legislation?

o because it would give rich states more power than poor states

o because it would make one state superior to another

o because such acts could dissolve the union itself

o because it would create the need for greater enforcement authority

Explanation:

The United States is a federal system. If states could disregard federal legislation, it undermines the unity and authority of the federal government. The Union is based on the idea of a collective nation - state with a certain level of federal supremacy. Disregarding federal laws by states could lead to a breakdown of the federal structure, as each state could act independently, which is a threat to the very existence of the United States as a unified nation.

Answer:

because such acts could dissolve the Union itself