Which of the following is NOT a type of heat transfer?

The concept of heat transfer involves the ways in which thermal energy moves from one location to another. The three primary modes of heat transfer are conduction, convection, and radiation.

Conduction refers to the transfer of heat through direct contact between materials, where energy is transferred from the hotter part of the material to the cooler part. Convection involves the transfer of heat by the movement of fluids (liquids or gases), where warmer, less dense parts of the fluid rise and cooler, denser parts sink, creating a circulation that transfers heat. Radiation is the transfer of heat in the form of electromagnetic waves, which can occur in a vacuum, such as the heat from the sun reaching the earth.

Reflection, however, does not fit into the category of heat transfer mechanisms. Instead, it describes the bouncing back of light or energy waves when they hit a surface. While reflection can impact the intensity of heat experienced on a surface (by preventing absorption, for example), it does not actually facilitate the transfer of thermal energy from one body to another. Thus, it is not classified as a mode of heat transfer, making it the correct answer to this question.