Because of the crazy large population.
Answer and Explanation:
Earths crust is broken into plates called tectonic plates. the plates move bc of convection currents in the earths mantle. convection currents are the movement caused with a liquid by the propencity of hotter and less dense matter to rise, and colder, thicker material to sink under the effect of gravitational pull, which as a result results in the transfer of heat. As a result these are moved by the heat composed by the common natural blight of radioactive component in the earth.
B, both in real history and this chart, America created the first atomic weapons, and Russian spies during WW2 wanted to have the advantage of such power, lest America have a monopoly on pure Force.
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The Gulf of Mexico and the Atlantic Ocean