Calorimetry is the science of determining the changes in energy of a system by measuring the heat exchanged with the
surroundings. describe a calorimeter

A calorimeter is a device used to measure the heat flow of a chemical reaction or physical change. The process of measuring this heat is called calorimetry. A basic calorimeter consists of a metal container of water above a combustion chamber, in which a thermometer is used to measure the change in water temperature.

I think the answer is B.