Question

what happens during heat transfer?
heat always flows from warm to hot.
heat always flows from cool to warm.
heat always flows from warm to cool.

Explanation:

Heat transfer is a fundamental concept in physics. According to the second law of thermodynamics, heat always flows from a region of higher temperature (warmer) to a region of lower temperature (cooler) until thermal equilibrium is reached. This is a natural process and does not occur in the reverse direction (from cold to warm or warm to hot in the sense of violating the temperature gradient) spontaneously.

Answer:

Heat always flows from warm to cool.