Question

When is thermal equilibrium achieved between two objects?

A.
when thermal energy is no longer transferred

B.
when one objects is hotter than the other

C.
when both objects have the same temperature

D.
when the particles in one object have more kinetic energy

Answer 1

Is there an option for both A and C?

Thermal equilibrium can be described as the point when no thermal energy is being transferred between the two objects. In other words, the objects have the same temperature. Choices A and C are essentially synonymous in this context. Hope I could help. 

Answer 2

The answer would be c. When both objects have the same temperature