Whenever energy changes form, people sometimes say that some energy is "lost." What is meant by this?
A. The energy is not truly lost; it transforms into forms that are not easily put to use.
B. The process of changing form reduces the total amount of energy in the universe.
C. Whenever energy changes form in one location, a corresponding change in the opposite direction must take place somewhere else.
D. Sometimes a "mistake" or an inefficiency in the transformation causes energy to be destroyed.