Answer:
493.9g is the correct answer
Sources are from NationalGeographic.org
"Decompression melting involves the upward movement of Earth's mosty-solid mantle. ... Decomposition melting often occurs at divergent boundaries, where tectonic plates separate. The rifting movement causes the buoyant magma below to rise and fill the space of the lower pressure. The rock then cools into new crust."
The answer is United States
