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
An IgG2 molecule is composed of? 
Select and explain. 
A. One gamma1 chain and two kappa chains, B. Two gamma1 chains and one kappa and one lambda chain, C. Two gamma1 chains and two kappa chains, D. Two gamma2 chains and two kappa chains
D: Two gamma2 chains and two kappa chains
Answer: D: Two gamma2 chains and two kappa chains 
Explanation: A single antibody molecule is made up of two heavy and two light chains As a rule both heavy and both light chains are identical IgG2 has two gamma2 heavy chains and two light chains (both kappa or both lambda).