What is the approximate percentage of oxygen in the atmosphere?

The approximate percentage of oxygen in the atmosphere is around 21%. This figure is consistent with what is accepted in scientific literature and measured data. Oxygen makes up a significant portion of the Earth's atmosphere, which is vital for sustaining life.

The 21% concentration allows for adequate respiration for humans and animals, and it plays a crucial role in combustion processes as well. Understanding this percentage is important for various fields, including firefighting where oxygen concentration can influence fire behavior and the efficiency of fire suppression.

The other options suggest either too low or too high a concentration of oxygen compared to the established average, highlighting the importance of accurate knowledge regarding atmospheric composition in both natural and emergency response contexts.