In the thermal equilibrium, the change in temperature is said to be zero in between the bodies. Thermal equilibrium is reached when both objects have the same temperature.
<h3>What is thermal equilibrium?</h3>
Thermal equilibrium is easily explained by the zeroth law of thermodynamics. If any two-body is at thermal equilibrium there is no change in the temperature of the body.
According to zeroth law if body A is in thermal equilibrium with body B and body B is in thermal equilibrium with C . So body A and C are also in thermal equilibrium.
In the thermal equilibrium, the net heat transfer is said to be zero in between the bodies.
Hence option A IS RIGHT. Thermal equilibrium is reached when both objects have the same temperature
To learn more about the thermal equilibrium refer to the link;
brainly.com/question/2637015
the answer to your question is 10.5 kJ