What percentage of the atmosphere is made up of gases other than nitrogen and oxygen?

The atmosphere is primarily composed of nitrogen and oxygen, making up approximately 78% and 21% of the total atmospheric composition, respectively. This leaves about 1% comprised of trace gases. These trace gases include argon, carbon dioxide, neon, helium, methane, krypton, and hydrogen, among others. Since the bulk of the atmosphere consists of nitrogen and oxygen, the role of the other gases is minimal, which is why the correct choice reflects that they account for around 1% of the total atmosphere. Understanding the proportions in the atmosphere helps to appreciate the significance and roles of various gases, particularly in processes such as respiration, photosynthesis, and climate regulation.