In Article I, Section 10, Clause 3, states are forbidden from keeping a standing army or navy. Why would the Constitution restrict a state from "keeping a standing army"?

This restriction is meant to prevent the states from assuming powers that the Constitution grants to the national government.

Supporting an army and navy is a difficult financial burden for a single state.

The states might use the army to overthrow the federal government.

State and federal armies would compete for limited resources.

Option A is the right answer.

Explanation:

The constitution was implemented in such a manner that no state shall impinge upon the centralized powers of the Union Government.

Founding fathers have prohibited the use of standing army during the time of peace as it would affect the liberty of the nation. Federalists feared that the states would become tyrannical if the standing army is allowed by it. Hence, the founding fathers have mentioned in the constitution that the congress have the powers to raise money and appropriate funds for standing army for not more than two years.

Anti-federalist favored standing army as it would safeguard the security of the citizens. But federalists felt that it would alarm the liberty and freedom of the nation and hence constitution allowed standing army but only during the time of peace it must be disbanded.