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: Microbiology
All of the following compounds are mitogens that stimulate human T cells to proliferate, EXCEPT: 
Select and explain. 
A. Lipopolysaccharide, B. Concanavalin A, C. Anti CD3 antibody, D. Phytohemagglutinin
A: Lipopolysaccharide
Answer: A: Lipopolysaccharide 
Explanation: All of the listed compounds are T-cell mitogens except lipopolysaccharide, which is a B-cell mitogen. Ref: Harrison's Principles of Internal Medicine, 17th Edition, Chapter 310, Page 2055