What does equilibrium temperature refer to?

Equilibrium temperature refers to the state at which two systems in thermal contact reach a balance where there is no net flow of heat between them. This state is achieved when both systems have the same temperature, meaning heat transfer has ceased. In this context, the correct answer accurately describes this concept by indicating that the equilibrium temperature is the point where temperatures balance each other out, with no temperature difference to drive heat transfer.

While the notion of a midpoint or average relating to temperatures might seem intuitive, the specific definition of equilibrium temperature emphasizes the cessation of heat transfer due to equal temperature levels. Understanding this principle is fundamental in thermodynamics, as it underscores the importance of temperature balance in thermal interactions.