What is the percentage of nitrogen in the air?

The correct answer reflects the composition of Earth's atmosphere, which is primarily made up of nitrogen. Nitrogen constitutes about 78% of the total volume of air we breathe, making it the largest component. This percentage is significant because it helps in maintaining the balance necessary for various processes, such as combustion and respiration. Understanding the atmospheric composition is essential for firefighters, as it influences fire behavior, smoke dispersion, and the effectiveness of certain fire-suppression agents. The other options greatly overstate the nitrogen content in the atmosphere, which is critical knowledge for anyone involved in emergency response and firefighting.