This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc. (W.B.C), Subject name: Pathology
All of the following stem cell populations are found within the bone marrow, except - 
Select and explain. 
A. Endothelial Progenitor cells, B. Myoblast Progenitor cells, C. Mesenchymal stem cells, D. Hematopoietic stem cells
B: Myoblast Progenitor cells
Answer: B: Myoblast Progenitor cells 
Explanation: Ans. (b) Myoblast Progenitor cells(Ref: Robbins 9th/pg 580-581)Endothelial Progenitor cells, Mesenchymal stem cells and Hematopoetic stem cells are found in the bone marrow.Mesenchymal stem cells are multipotent stromal cells constituting 0.001-0.01% of bone marrow cells.