The dry bulb temperature at the exit of the air washer is closed to

Question

Air (at atmospheric pressure) at a dry bulb temperature of 40⁰C and wet bulb temperature of 20⁰C is humidified in an air washer operating with continuous water recirculation. The wet bulb depression (i.e. the difference between the dry and wet bulb temperatures) at the exit is 25% of that at the inlet. The dry bulb temperature at the exit of the air washer is closed to                                                                                           

      (a) 10⁰C                                                              (b) 20⁰C

      (c) 25⁰C                                                              (d) 30⁰C