Commonly chosen subjects by candidates for the UPSC main examination include Geography, Political Science, Sociology, Public Administration, and Anthropology. These subjects are favored because they align with the general studies syllabus and provide a structured content framework for aspirants. Some candidates also select optional subjects based on their academic background or personal interest, ensuring a solid foundation for both the mains and the general studies papers. Ultimately, selecting the right subject can enhance performance and comprehension during the examination.