According to the Second Law of Thermodynamics, heat flows from a:

The Second Law of Thermodynamics states that heat naturally flows from a higher temperature body to a lower temperature body, meaning that energy will move from areas of higher thermal energy to areas of lower thermal energy until thermal equilibrium is reached. This principle underpins many natural processes and is fundamental in the study of thermodynamics, particularly in the context of heat engines and refrigeration systems.

This law is observed in everyday life; for instance, when you place a hot cup of coffee in a cooler room, the heat from the coffee will transfer to the surrounding air until both reach a similar temperature. Understanding this principle is essential for refrigeration and air conditioning systems, where the goal is often to extract heat from a lower temperature space and reject it to a higher temperature environment, utilizing work to force this naturally opposite flow of heat.

The other choices do not align with this fundamental concept. For example, the idea that heat flows from a cold substance to a hotter substance contradicts the natural behavior observed in thermodynamic systems, which is why the correct choice focuses on the movement of heat from the higher temperature to the lower temperature body.