Optional subjects in the UPSC Main Examination include a range of disciplines allowing candidates to showcase their strengths and specialization. Candidates can choose from subjects such as Anthropology, Geography, Public Administration, Political Science, and Sociology, among others. The variety of options provides candidates an opportunity to select subjects they are either passionate about or well-versed in, often leading to better performance. Choosing the right optional subject is a critical decision, as it can significantly influence overall scores in the examination.