Please help me Heat travels in slow convection currents of solid materials within Earth's mantle. Heat that rises in these currents
A. is a by-product from the decay of Earth's radioactive isotopes.
B. is provided externally by the Sun.
C. is a by-product of frictional forces between Earth's tectonic plates as they slide past one another.
D. is provided externally by gravitational energy in the Solar System.

A. is a by-product from the decay of Earth's radioactive isotopes.

Explanation:

If all convection currents on Earth stopped that would be a natural disaster. The amount of heat which the sun radiates at us sets the temperature of the Earth's surface. So if convection completely stopped the high and low temperatures would force people and animals to move away from the poles and equator.

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