What statement represents the first law of thermodynamics?

Correct Answer: Option D — When heat is transferred from one body to another, the internal energy given up by the first body must be equal to the internal energy taken up by the second body.

The First Law of Thermodynamics, or the law of conservation of energy, states that energy cannot be created or destroyed. In a closed system, the heat energy lost by a hot body must be exactly equal to the heat energy gained by the cold body, assuming no external losses.