Within an air mass, temperature and humidity vary, but pressure does not.
Answer: Option A
Step-by-step 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.