Answer: (B) - Second law of thermodynamicS
Heat transfer takes place according to the second law of thermodynamics.
The second law of thermodynamics points out that the heat is transferred from one body to another body only if the two bodies are at different temperatures, i.e., the heat flows from the high-temperature body to the body at low temperature.
According to Kelvin-Plank: It is impossible for any system to operate in a thermodynamic cycle and deliver a net amount of energy by working to its surroundings while receiving heat energy from a single thermal reservoir.
According to Clausius: It is impossible to construct a device as a heat pump that operates in a cycle and produces no effect other than transferring heat from a lower temperature to a higher temperature body.
Hence, the heat transfer occurs according to the second law of thermodynamics. The first law failed to differentiate heat and work and does not explain the direction of the flow of heat.
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