A unit mass of a substance undergoes an irreversible process from state 1 to state 2 while gaining heat from the surroundings at temperature T in the amount of q. If the entropy of the substance is s1 at state 1, and s2 at state 2, the entropy change of the substance s during this process is
(a) ∆s < s2 - s1
(b) ∆s > s2 - s1
(c) ∆s = s2 - s1
(d) ∆s = s2 - s1 q/T
(e) ∆s = s2 - s1 + q/T