This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Idiotypic class of antibody is determined by - \nSelect and explain. \nA. Fc region, B. Hinge region, C. Carboxy end, D. Amino end', 'role': 'user'}, {'content': 'Answer: D \nExplanation: An idiotype is a shared characteristic between a group of immunoglobulin or T cell receptor (TCR) molecules based upon the antigen binding specificity and therefore the structure of their variable region. The variable region of antigen receptors of T cells (TCRs) and B cells (immunoglobulins) contain complementarity-determining regions (CDRs) with unique amino acid sequences Ref: www.mayoclinic.com', 'role': 'assistant'}]