Optional subjects hold significant importance in the overall ranking of candidates in the UPSC examination. The score in the optional subject paper directly contributes to the total marks in the Mains Examination, which is decisive for final rankings. Choosing the right optional subject can thus be crucial for maximizing potential scores, as subjects aligned with a candidate's strengths and interests often yield better performance. Therefore, careful selection based on aptitude and familiarity can greatly influence success in the examination.