25. A gas with a fixed number of molecules does 32 J of work on its surroundings, and 16 J of heat are transferred from the gas to the surroundings. What happens to the internal energy of the gas?
(A) It decreases by 48 J .
(B) It decreases by 16 J .
(C) It increases by 16 J .
(D) It increases by 48 J .