This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology Pa 1 (Immune Response, Antigen-Antibody Reactions, Hypersensitivity, Structure of Immune System, Immunodeficiency Disorders), Subject name: Microbiology
[{'content': 'The complementarity-determining regions are- \nSelect and explain. \nA. Restricted to light chains, B. Are in the constant pa of the Ig molecule, C. Binds to Fc receptor, D. Are concerned in antigen recognition', 'role': 'user'}, {'content': 'Answer: D \nExplanation: In the variable region of the H and L domains, maximum sequence variation is concentrated in a few discrete regions called hyperevariable regions ( HV) . HV regions form the antigen binding site of the antibody molecule which is complementary to the structure of the epitope and are called Complementary Determining Regions (CDRs)', 'role': 'assistant'}]