Question

As the Earth formed, naturally occurring radioactive material _____________. increased the planet’s gravity disappeared heated the planet poisoned the soil

Answer 1

When the Earth formed, the radioactive materials that naturally occurred in the environment heated the planet. These radioactive materials generate heat when they decay. This heat generated is then transferred to the surface of the Earth.

The radioactive materials have no role in increasing the gravity of the Earth or poisoning the soil. Moreover, the naturally occurring radioactive materials are still present and has not disappeared.

Hence, the answer is heated the planet.