In counter flow heat exchangers

Q. In counter flow heat exchangers

A.            both the fluids at inlet (of heat ex¬changer where hot fluid enters) are in their coldest state

B.            both the fluids at inlet are in their hot¬test state

C.            both the fluids .at exit are in their hottest state

D.            one fluid is in hottest state and other in coldest state at inlet

Answer: both the fluids at inlet are in their hot¬test state