8. Which one of the following statements of the second law of thermodynamics is correct?
(A) In a reversible process the entropy of an isolated system stays constant; in an irreversible process the entropy decreases.
(B) In a reversible process the entropy of an isolated system increases; in an irreversible process the entropy stays constant.
(C) It is impossible for a cyclical device to transfer heat continuously from a cold body to a hot body without the input of work or other effect on the environment.
(D) It is possible for a heat engine that operates in a cycle to convert its heat input completely into work.
(E) Every cyclical heat engine has a greater efficiency than a reversible engine operating between the same two temperatures.