Heat is...

a). a measure of temperature.
b). a measure of the change in temperature.
c). a measure of thermal energy.
d). a measure of thermal energy transferred between two bodies at different temperature.

Why?

Pay particular attention to the first sentence of this site.

https://en.wikipedia.org/wiki/Heat

The correct answer is c) a measure of thermal energy.

To understand why, let's break down the other options:

a) Heat is not simply a measure of temperature because temperature refers to the average kinetic energy of the particles in a substance, while heat refers to the total amount of thermal energy present in the substance.

b) Heat is not just a measure of the change in temperature because temperature change is only a result of heat transfer. Heat itself is the energy that flows from a body at a higher temperature to a body at a lower temperature, causing the temperature change.

d) Although heat is indeed transferred between two bodies at different temperatures, this option specifically mentions transfer and ignores the fact that heat can exist even without transfer. Heat is the thermal energy possessed by an object, irrespective of whether it is transferred or not.

So, c) is the most accurate answer because heat is the measure of the total thermal energy present in a substance or object.