Which of the Following Statements Concerning Humidity Is Incorrect

Which of the following statements concerning humidity is incorrect?

A) A sling psychrometer is an instrument comprised of two thermometers
B) If all other variables remain constant,a decrease in temperature leads to a decrease in humidity
C) Relative humidity compares the amount of water vapor present to the maximum amount that the air can hold at that temperature,expressed as a percentage.
D) Air at 20 degrees Celsius can hold three times as much water vapor as air at 0 degrees Celsius
E) If air is cooled it will eventually reach saturation