Which of the following is the most abundant element in the human body?

• A. Carbon
• B. Oxygen
• C. Hydrogen
• D. Nitrogen

Answer: (B)

Verified step by step guidance

1. Understand that the question asks for the most abundant element in the human body by mass or number of atoms.
2. Recall that the human body is primarily composed of water (H\_2O), which contains oxygen and hydrogen, and also contains significant amounts of carbon and nitrogen in organic molecules.
3. Recognize that oxygen is a major component of water and organic molecules, making it the most abundant element by mass in the human body.
4. Compare the relative abundance of the elements: oxygen, carbon, hydrogen, and nitrogen, noting that oxygen typically makes up about 65% of the body's mass.
5. Conclude that oxygen is the most abundant element in the human body based on its prevalence in water and organic compounds.