An air handler is a large unmixed heat exchanger used for comfort control in large buildings. In one such application, chilled water (c_p = 4.2 kJ/kg · K) enters an air handler at 5°C and leaves at 12°C with a flow rate of 1000 kg/h. This cold water cools 5000 kg/h of air (c_p = 1.0 kJ/kg · K) which enters the air handler at 25°C. If these streams are in counter-flow and the water-stream conditions remain fixed, the minimum temperature at the air outlet is
(a) 5°C

(b) 12°C

(c) 19°C

(d) 22°C

(e) 25°C