how do temperature, humidity, and pressure vary within an air mass?

temperature and humidity vary, but pressure does not.

temperature, humidity, and pressure are basically the same all through an air mass.

temperature at the border of an air mass is always higher than in the middle.

humidity makes the pressure in an air mass increase.

Within an air mass, temperature and humidity vary, but pressure does not.

Option A

Explanation:

Air mass as the name suggest, is a mass or large amount of air which consists of temperature and moisture in it. The temperature will vary according to the position of air mass, for example- temperature in the middle of air mass will always be lower.

Similarly, humidity also varies in air mass, if the temperature of the air decrease, it will remain as it is. But on other environment it may either add water mass or can lose it. So at any given time, temperature and humidity may vary, but pressure doesn’t.  

a low four-wheeled open carriage of a kind formerly used in russia.