An Amendment is added to the US constitution after which of these events A) The president signs it.
B) The 1/2 of Congress ratifies it.
C) the 3/4 of the state ratify it.
D) The American people vote to added it.

The Amendment proposed become valid and added to the US constitution after the 3/4 of states ratify it.

Amendment refers to the alteration, addition or subtraction made to the constitution original provision.

For the proposal of the amendment, the Congress must call a convention upon application of the legislatures of two-thirds of the states.

The Amendments become valid when its is been ratified by the legislatures or conventions in three-fourths of the states.

Therefore, the Option C is correct.

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C) the 3/4 of the state ratify it.

Explanation:

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answer; by working independently, the states have a high likelihood of developing innovative solutions that can be employed in other states;