A system of 100 kg mass undergoes a process in which its specific entropy increases from 0.3 kJ/kgK to 0.4 kJ/kgK. At the same time, the entropy of the surroundings decreases from 80 kJ/K to 75 kJ/K. The process is
(a) Reversible and isothermal
(b) Irreversible
(c) Reversible only
(d) Isothermal only