Which best describes the direction of heat?

Heat naturally flows from a warmer substance to a cooler substance due to the second law of thermodynamics, which states that energy tends to disperse or spread out when not constrained. This transfer occurs because thermal energy is exchanged between particles, moving from areas of higher kinetic energy (typically warmer substances) to areas of lower kinetic energy (cooler substances) until thermal equilibrium is reached. This principle is fundamental in understanding processes such as convection, where warmer fluids rise while cooler fluids sink, creating a cycle of heat transfer. The direction of heat transfer is crucial in many scientific and engineering applications, as it influences everything from weather patterns to the design of heating systems.