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: Pathology
[{'content': 'Human leukocyte antigen (HLA) which plays an impoant role in graft rejection is present on chromosome: \nSelect and explain. \nA. Sho arm of chromosome 6, B. Long arm of chromosome 6, C. Sho arm of chromosome 3, D. Long arm of chromosome 3', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The genes for the HLA antigens are clustered in the major histocompatibility complex (MHC), located on the sho arm of chromosome 6. Three of these genes (HLA-A, HLA-B, and HLA-C) code for the class I MHC proteins. Several HLA-D loci determine the class II MHC proteins (i.e., DP, DQ, and DR). Ref: Levinson W. (2012). Chapter 62. Major Histocompatibility Complex & Transplantation. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.', 'role': 'assistant'}]