What core principle of thermodynamics states that heat will never spontaneously flow from a colder body to a hotter body?

The question asks about the core principle of thermodynamics that states heat will never spontaneously flow from a colder body to a hotter body.

• The Zeroth Law deals with thermal equilibrium, stating that if two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
• The First Law is about the conservation of energy, stating that energy cannot be created or destroyed.
• The Second Law states that the total entropy of an isolated system can only increase over time. A direct consequence of this law (Clausius statement) is that heat cannot spontaneously flow from a colder body to a hotter body without external work being done.
• The Third Law deals with the entropy of a system as its temperature approaches absolute zero.

The principle described in the question is a fundamental aspect of the Second Law of Thermodynamics.

The correct answer is D.
D) The Second Law