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
Which of the following phospholipids do not contain glycerol 
Select and explain. 
A. Lecithin, B. Phosphatidyl serine, C. Sphingomyelin, D. Phosphatidyl inositol
C: Sphingomyelin
Answer: C: Sphingomyelin 
Explanation: Sphingomyelin contains sphingosine instead of glycerol.