The selection of an optional subject significantly influences main exam preparation, as it determines the focus and depth of study. Candidates should select a subject they are passionate about and possess an understanding of, as this can facilitate in-depth learning. A well-chosen optional subject can also enhance overall scores, as candidates are likely to write better when they are genuinely interested. Furthermore, the availability of relevant study materials and faculty guidance must be considered, ensuring efficient preparation strategies and maximizing chances for success.