If the amount of water vapor in the air remained constant, but the air temperature increased throughout the day, the relative humidity would

Decrease

Explanation:

Relative humidity is both a function of water vapor in the air and temperature. By increasing the temperature, you increase the amount of water vapor the air can hold. This is because hot air has the ability to hold more moisture than cool air. Therefore, as the temperature increases, the relative humidity is bound to reduce.

it takes on an electronical energy