An isolated system
(A) is a specified region where transfers of energy and mass takes place
(B) is a region of constant mass and only energy is allowed to close the boundaries
(C) is one in which mass within the system is not necessarily constant.
(D) cannot transfer either energy of mass to or from the surroundings.
(D) An isolated system is one which is separated so that mass and energy of the system cannot be transferred to or from the surroundings.