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

Oxygen is the most abundant element in the human body, accounting for a significant portion of bodily mass, primarily due to its presence in water (H2O), which makes up a large part of human composition. Our bodies are approximately 60% water, and since oxygen is a major component of water, it follows that it is also the most plentiful element. In addition to being a critical part of water, oxygen is essential for cellular respiration, an important process that provides energy for all bodily functions. The presence of oxygen in various organic molecules and in tissues supports numerous biological processes, making its abundance in the human body crucial for sustaining life.

While carbon, hydrogen, and nitrogen are also vital elements found in the human body—forming key components of proteins, nucleic acids, and other organic molecules—oxygen still preceeds them in terms of abundance due to its significant role in water content and cellular function.