Final answer:
The four elements that comprise more than 90% of body matter are oxygen, carbon, hydrogen, and nitrogen, which are critical in forming the biological molecules essential for life.
Step-by-step explanation:
The four elements that comprise more than 90% of the body matter are oxygen (O), carbon (C), hydrogen (H), and nitrogen (N). These elements are crucial because they form the nucleic acids, proteins, carbohydrates, and lipids that constitute the fundamental components of living matter. All living organisms, including the human body, rely on these elements to maintain structure and function. For instance, carbon's ability to form four chemical bonds makes it exceptionally versatile and central to the formation of complex molecules. Nitrogen and oxygen are also vital for constructing a vast array of molecules, whereas hydrogen, the most abundant element in the universe, is essential in the formation of water and organic compounds within the body.