What is the purpose of a thermal insulator?

A thermal insulator serves primarily to reduce heat transfer between two bodies, which is why this choice is the correct answer. Insulators are materials that have low thermal conductivity, meaning they do not allow heat to pass through them easily. This characteristic makes them valuable in a variety of applications where it's important to maintain a temperature difference, such as in buildings, cooking utensils, and thermal blankets.

By minimizing heat transfer, thermal insulators help to conserve energy, enhance efficiency in heating and cooling systems, and provide comfort and safety in both industrial and residential settings. They can effectively prevent heat loss in colder environments or protect against excess heat in warmer conditions.

The other options do not accurately reflect the primary function of thermal insulation. For instance, enhancing heat transfer would be the role of conductors, not insulators. Keeping temperature constant might occur indirectly as a result of reducing heat transfer, but it is not the primary purpose of an insulator itself. Conducting heat from one body to another contradicts the very nature of what a thermal insulator is intended to do.