Answer: The correct answer is (d).
Step-by-step explanation:
Dew point is defined as the temperature at which the air becomes saturated (no more capacity to hold water vapors) with water vapors. At this temperature,some of the water vapors starts getting condensed into water droplets. The dew point temperature is always lower (sometimes equal) then the air temperature.
From the given option the most relevant option going with definition of dew point is option(D).