In the final step of adding an Amendment to the Constitution, who gives the final approval? The States
Supreme Court
Congress
A Popular vote

I think it's the states.

Explanation: 38 out of 50 states have to agree to add an amendment to the constitution.

they required less loading and unloading

explanation:

the shipping container improved shipping because it cut down on unloading time by three weeks, eliminated wasted space, and allowed ships to carry.

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.