Final answer:
The stable gases in the atmosphere from most to least abundant are Nitrogen, Oxygen, and Argon. Nitrogen is the primary component at 78%, followed by Oxygen at 21%, and Argon at 0.9%. So, the correct answer is option a.
Step-by-step explanation:
The three stable (i.e., nonvariable) gases in the atmosphere, in order of abundance from most to least, are Nitrogen, Oxygen, Argon. Nitrogen makes up approximately 78% of the atmosphere, serving as the solvent for this gaseous solution.
Oxygen is the next most abundant at about 21%, essential for life and combustion processes. Argon, as a noble gas, comes after oxygen, constituting about 0.9% of the atmosphere, and is commonly used for its unreactive properties in applications such as welding and light bulbs. So, the correct answer is option a.