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': 'Effector binding region of the antibody is \nSelect and explain. \nA. Constant region of heavy chain, B. Variable region of heavy chain, C. Constant region of heavy and light chain, D. Variable region of heavy and light chain', 'role': 'user'}, {'content': "Answer: D \nExplanation: Within the variable regions of both the Light and Heavy chains are subregions consisting of extremely variable amino acid sequences, called hypervariable, that cooperate in space to form the antigen-binding siteReference: Jawetz, Melnick, & Adelberg's Medical Microbiology; 27th edition; Chapter 8; Immunology", 'role': 'assistant'}]