Which class of nutrient is composed of carbon, hydrogen, oxygen, and nitrogen?

Proteins are complex molecules that are essential for many bodily functions, and they are composed of carbon, hydrogen, oxygen, and nitrogen. The presence of nitrogen is particularly significant because it distinguishes proteins from other macronutrients such as carbohydrates and fats, which do not contain nitrogen. Proteins are made up of amino acids, which are the building blocks of protein, and these amino acids contain nitrogen in their structure. This makes proteins vital for growth, repair of tissues, and various metabolic processes.

Carbohydrates are primarily made up of carbon, hydrogen, and oxygen, but they lack nitrogen. Fats and oils, which are lipids, also consist mainly of carbon, hydrogen, and oxygen, and do not include nitrogen. Electrolytes are minerals that dissolve in water and are important for maintaining fluid balance in the body; they do not consist of the elements that make up proteins. Thus, the unique composition of proteins with nitrogen makes it the correct answer in this context.