The correct answer is: D. All of the above.
Humidity is the amount of water vapor in the air. It is measured as a percentage of the total amount of water vapor that the air could hold at a given temperature. The higher the temperature, the more water vapor the air can hold. This is why it is more humid in the summer than in the winter.
The humidity of the air also depends on the location. Places near water, such as oceans and lakes, tend to have higher humidity than places far from water. This is because water evaporates into the air from the surface of the water.
The weather can also affect the humidity of the air. When it is raining or snowing, the air is more humid. This is because the water droplets in the rain or snow add water vapor to the air.
In conclusion, the humidity of the air depends on the temperature, location, and weather.