The decay of atoms is a source of internal energy for the Earth because is produced in the decay process.

The correct answer is - heat.

Explanation:

Earth has two energy sources internal and external energy. The external energy comes from mainly the sun while the internal energy comes from two major sources gravitation energy of the earth and the radioactive decay of atoms.

The earth's process of decaying atoms is an internal energy source that is provided by the producing heat by the disintegration of natural atoms inside the earth.

metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks (protoliths), without the protolith melting into liquid magma (a solid-state change). the change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. i hoped i !