Answer:
The correct answer is option C.
Explanation:
The radioisotopes in the Earth's interior are not in pure form and exhibit various entrenched impurities and are interspersed. Thus, when a neutron is discharged by a decaying atom, its occurrences of hitting another atom of radioisotope in order to continue the chain reaction becomes lower in comparison to the man-made nuclear reactor. In this manner, the radioactive chain reaction in the interior of the Earth is not well-sustained.
