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
E. any combination is possible depending on design of heat exchanger