This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
The nitrogen of the body is supplied by: 
Select and explain. 
A. Triacyl glycerol, B. Proteins, C. Glucose, D. Lipids
B: Proteins
Answer: B: Proteins 
Explanation: Proteins are polymers of amino acid. Proteins contain carbon, hydrogen, oxygen and nitrogen as the major components. Nitrogen is characteristic of protein. On an average, the nitrogen content of ordinary proteins is 16% by weight.