What mechanism primarily causes heat transfer through solids?

The primary mechanism that causes heat transfer through solids is conduction. This process involves the transfer of thermal energy through direct contact of particles in a material. When one part of a solid is heated, its particles begin to vibrate more vigorously. These vibrating particles collide with neighboring particles, transferring some of their energy to them. This chain reaction continues throughout the solid, allowing heat to move from the hotter region to the cooler region.

Conduction is particularly effective in solids because the particles are closely packed together, allowing for efficient energy transfer. In contrast, convection primarily occurs in fluids (liquids and gases) where the movement of the fluid itself carries heat, while radiation does not require a medium and occurs through electromagnetic waves. Evaporation is a process related to phase change and primarily involves heat transfer in liquids, not solids. Therefore, conduction is the correct choice for heat transfer in solids.