During conduction, energy transfer occurs through:

During conduction, energy transfer occurs primarily through the direct contact of objects. This process involves the transfer of thermal energy between molecules or atoms when they are in direct physical contact. When one object is heated, its particles vibrate more quickly and, upon colliding with neighboring, cooler particles, transfer some of their energy to those particles. This direct interaction allows for efficient energy transfer, making conduction an important mechanism for heat transfer in solids.

Conduction operates most effectively in solids because the particles are closely packed together, facilitating the process of energy transfer through physical contact. In contrast, other mechanisms such as the movement of air molecules (associated more with convection) or the emission of infrared radiation (related to radiation) do not involve the direct contact between materials. Mixing of different fluids relates to convection, where heat is transferred by the movement of fluid masses rather than direct contact between particles. Therefore, the fundamental characteristic of conduction being reliant on direct contact makes this answer the most accurate representation of the process.