Question

what is heat?
when energy is destroyed
the flow of energy between two objects of unequal temperature
loss of energy between two objects with unequal temperatures.
when energy is created

Explanation:

Heat is defined as the flow of energy between two objects due to a temperature difference. Energy cannot be created or destroyed (law of conservation of energy), so the first and last options are incorrect. "Loss of energy" is too vague compared to "flow of energy", which is the precise term.

Answer:

The flow of energy between two objects of unequal temperature.