This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
The following is not a constitute of cell membrane: 
Select and explain. 
A. Cholesterol, B. Carbohydrates, C. Proteins, D. Nucleic acids
D: Nucleic acids
Answer: D: Nucleic acids 
Explanation: Cell is made of 3 substances: Lipid Proteins Carbohydrates