For the unsaturated air, the relationship of size among the dry bulb temperature, wet bulb temperature and dew point temperature is ().
A . Dry bulb temperature> Dew point temperature> Wet bulb temperature
B . Dry bulb temperature> wet bulb temperature> dew point temperature
C . Wet bulb temperature> dew point temperature> dry bulb temperature
D . wet bulb temperature> dry bulb temperature> dew point temperature
Answer: B