A. 09 percent
B. 21 percent
C. 15 percent
D. 03 percent
🧠 Explanation:
The atmosphere contains approximately 21% oxygen, essential for human and animal survival. For environmental science students, this highlights atmospheric composition, making it a key topic for studying air quality, respiratory biology, and environmental systems. Oxygen supports combustion and ecosystems. Understanding its proportion aids in analyzing climate and pollution impacts. It’s essential for studying environmental science, atmospheric chemistry, and ecological balance. Studying oxygen levels offers insights into how air composition affects life, climate change, and environmental health, crucial for scientists, ecologists, and policymakers addressing air quality, sustainability, and the global impact of atmospheric changes on ecosystems.
