Generally, subjects considered optional in the UPSC Mains Examination include Anthropology, Sociology, Geography, along with several others like History and Political Science. Aspirants can choose from a wide array, depending on their interest and prior knowledge. The optional subject accounts for a significant part of the total marks in the examination, necessitating thorough preparation. Selecting a subject that aligns with one's strengths can effectively improve overall performance in the Mains.