Final answer:
Heat generation in planets occurs through gravitational pull, nuclear fusion, and conduction.
Step-by-step explanation:
Heat generation in planets occurs through all of the above: gravitational pull, nuclear fusion, and conduction.
pull plays a role in generating heat in planets through the process of gravitational contraction, where the planet's mass collapses under its own gravity and releases energy as heat.
Nuclear fusion is another mechanism of heat generation in stars, including planets. This process involves the fusion or joining together of atomic nuclei to release a tremendous amount of energy in the form of heat and light.
Conduction is the transfer of heat through direct contact between objects or substances. In the context of planets, conduction occurs within their interiors, allowing heat to be conducted from the hotter regions to the cooler ones.