What is true about the dew point under these conditions?
A. The dew point is lower than 23°C.
B. The dew point is equal to 23°C.
C. The dew point is higher than 23°C.
D. The dew point is 100°C.

B. The dew point is equal to 23° C.

Explanation:

This is regarding humidity of dry bulb thermometer and the wet bulb thermometer. The dew point is mostly equal to or lesser than the given temperature, here it is 23°C that is the temperature of the dry bulb thermometer.If the relative humidity is 100% then the temperatures of both dry bulb  and wet bulb are equal, and so the dew point is equal to 23° C and not lesser than that.By considering this above explanation we can conclude that Option B ( ie The dew point is equal to 23° C ) as correct answer