The Chairman of the Finance Commission must have experience in public affairs. This means that they should have knowledge and understanding of how the government operates and be familiar with public policy and administration. They should have a strong background in dealing with financial matters and an understanding of economic principles. While options 1, 2, and 3 may also possess relevant skills and knowledge, option 4 is the most appropriate as it encompasses a wider range of expertise needed for the role. It is important for the chairman to have a broad understanding of public affairs in order to effectively carry out their responsibilities and make informed decisions regarding financial matters.