Which of the following statements best describes energy conservation in heat engines? A. The heat engine's energy is exhausted to the outside system.

B. The sum of the heat placed into the hot reservoir and the work collected equals the energy transferred from the cold reservoir.

C. A volume of heat is discharged to the cold body where some waste energy is in a form of heat in this engine.

D. The work derived from the heat engine is equal to the energy placed into the hot reservoir. ​