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
[{'content': 'Which of the following phospholipids do not contain glycerol \nSelect and explain. \nA. Lecithin, B. Phosphatidyl serine, C. Sphingomyelin, D. Phosphatidyl inositol', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Sphingomyelin contains sphingosine instead of glycerol.', 'role': 'assistant'}]