Answer:
temperature
Step-by-step explanation:
For any transfer of heat energy from one system to other it always requires temperature gradient.
So here we can say that when two bodies are at different temperatures then the Heat is transferred from one object at high temperature to other object at lower temperature.
The transfer of energy is of dynamic type in which if two bodies comes to same temperature then heat given by one body to other body is equal in magnitude to the heat given by other body.
So here if the temperature of two objects are equal then in that case the net thermal energy transferred will be zero.
So here correct answer would be TEMPERATURE