A hotfluid enters the counter flow heat exchanger at $$120^\circ C$$ and leaves at $$80^\circ C$$. A cold fluid enters the heat exchanger at $$60^\circ C$$. The mean temperature difference between the two fluids is (Assume the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal)

A

$$15^\circ C$$

B

$$35^\circ C$$

C

$$40^\circ C$$

D

$$20^\circ C$$