What are fossil fuels primarily used for?

Fossil fuels are primarily used for energy production because they serve as a significant source of energy for various applications, including electricity generation, heating, and powering vehicles. They release energy when burned, which can then be converted into usable forms of energy, such as electricity in power plants or mechanical energy in cars.

While other options mention specific uses of fossil fuels, like transportation or electrical generation, they do not encompass the full range of applications that fossil fuels supply energy for; they are integral to a broader category of energy production that includes industrial processes and residential heating as well. Thus, the choice highlighting energy production captures the comprehensive role fossil fuels play in meeting energy needs.