23. A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by 62°C, the efficiency of the engine is doubled. The temperatures of the source and sink are
(a) 80°C, 37°C (b) 95°C, 28°C
(c) 90°C, 37°C (d) 99°C, 37°C
Answer-d
(4)