The correct answer is D. N2.
Nitrogen (N2) is the most abundant gas in the Earth’s atmosphere, making up about 78% of the air we breathe. It is a colorless, odorless, and tasteless gas that is essential for life. Nitrogen is used by plants to create proteins and other essential molecules, and it is also used by animals to create DNA and RNA.
Oxygen (O2) is the second most abundant gas in the Earth’s atmosphere, making up about 21% of the air we breathe. It is a colorless, odorless, and tasteless gas that is essential for life. Oxygen is used by cells to produce energy, and it is also used in the combustion of fuels.
Carbon dioxide (CO2) is a greenhouse gas that is produced when fossil fuels are burned. It is also produced by natural processes such as respiration and volcanic eruptions. CO2 is a colorless, odorless, and tasteless gas that is essential for plant growth. However, too much CO2 in the atmosphere can contribute to climate change.
Hydrogen (H2) is a colorless, odorless, and tasteless gas that is the lightest element in the universe. It is the most abundant element in the universe, but it is not very abundant in the Earth’s atmosphere. Hydrogen is used in a variety of industrial processes, and it is also used as a fuel in fuel cells.