What are the five COHNS elements that make up human hair and skin?

The correct answer identifies the five key elements that compose human hair and skin as carbon, oxygen, hydrogen, nitrogen, and sulfur. These elements are fundamental building blocks of proteins and other organic molecules that are vital to the structure and function of hair and skin.

Carbon is central to forming organic compounds and is the backbone of amino acids, which are the building blocks of proteins such as keratin found in hair and skin. Oxygen is essential for respiration and metabolic processes and is also present in water, vital for maintaining skin hydration. Hydrogen contributes to the biochemical compounds that form acids and proteins. Nitrogen is a critical component of amino acids and plays a significant role in the structure of proteins. Finally, sulfur is important for the formation of disulfide bonds in proteins, which help in maintaining the structural integrity of hair.

The other options contain elements that are not relevant to the composition of hair and skin. For example, elements like copper and gold, though valuable in various contexts, are not foundational to human hair and skin composition. Similarly, elements such as silicon and phosphorus, while important in other biological contexts, do not pertain specifically to the fundamental building blocks of hair and skin.