Final answer:
kcal/m2hr is a unit for measuring the rate of heat transfer. It denotes the amount of energy in kilocalories transferred per square meter per hour.
Step-by-step explanation:
kcal/m2hr is a unit used to measure the rate of heat transfer. The kilocalorie (kcal) is a unit of energy equivalent to 1,000 calories and is defined as the amount of energy necessary to raise the temperature of one kilogram of water by 1°C. This measurement is commonly used in the context of energy balance, such as calculating the net rate of radiant heat transfer from surfaces, as described by the Stefan-Boltzmann law.
The use of kcal per square meter per hour allows reporting the quantity of heat energy that is transferred over a certain area during a given period of time. Therefore, in the question provided, the correct answer would be (c) Heat.