Answer:
B
Step-by-step explanation:
The most abundant gas is actuculy nitrogen (N). Nitrogen makes up about 78 percent of the gases in the atmosphere. The second most abundant gas is oxygen (O), which makes up about 21 percent. The remaining 1 percent is made of argon (Ar), carbon dioxide (CO2), water vapor, and other trace gases. Nitrogen, oxygen, argon, and carbon dioxide are the primary gases in the atmosphere.