The effectiveness of the HE is

Question

In certain HE, both the fluids have identical mass flow rate-specific heat product. The hot fluid enters at 76⁰C and leaves at 47⁰C, and the cold fluid entering at 28⁰C leave at 55⁰C. the effectiveness of the HE is                                                                                                                                                        

      (a) 0.16                                                               (b) 0.58

      (c) 0.72                                                               (d) 1.0