The correct answer is: C. 4 to 5 per cent
The maximum water vapor content in the atmosphere is about 4 to 5 per cent. This means that for every 100 grams of air, there are about 4 to 5 grams of water vapor. The amount of water vapor in the air can vary depending on the temperature and humidity.
The temperature of the air affects the amount of water vapor that the air can hold. Warmer air can hold more water vapor than cooler air. This is why it is more humid in the summer than in the winter.
The humidity of the air is the amount of water vapor that is in the air compared to the maximum amount of water vapor that the air can hold. The humidity can be expressed as a percentage. For example, if the humidity is 50%, then the air is holding half of the maximum amount of water vapor that it can hold.
The amount of water vapor in the air can also affect the weather. When the air is saturated, or holding as much water vapor as it can, it can cause clouds and precipitation.