What Is the Difference Between a Variable and Permanent Gas

What is the difference between a variable and permanent gas?

A) Variable gases have less effect on weather and climate than permanent gases.
B) Abundance of variable gases in the atmosphere change and abundance of permanent gases do not.
C) Variable gases comprise more of the atmosphere than permanent gases.
D) Variable gases are heavier than permanent gases.
E) Permanent gases are at a higher temperature than variable gases.