The water content in the atmosphere ________

in the question, water content is asked (water content = absolulte humidity)
But in solution, relative humidity is mentioned. Relative humidity is not a water content its just a ratio of water content and available and the capacity of water content at specific temperature.

so.
even if temperature is increased, water content remain always same in a given volume of air. (no change in absolute humidity)

conclusion:
in a given situation option (a) is right answer.
but a quetion arises, if temperature decteases below dew point, then vapour condensed to water, but still remain in air. so water content is independant of temperature,
But the capacity of holding water is depend on temperature.
hope you understand my point.