Optional subject plays a vital role in UPSC exam , altogether these optional subjects are consisting of 500 marks in the total of 1750 marks in the subjective paper and hence making it of higher chances to score. As this section is dependent on your choice and hence choosing the right subject in order to maximize your score out of 500 marks and hence resulting in an increase in the overall marks of the subjective examination. Which make it equally important to choose your optional subject wisely.
If you select good and scoring subject as your optional subject you can get as many marks you want and make it to merit list and can reduce your pressure of interview for some Marks. As a UPSC perspective you show them that you are good and have knowledge plus analytical skill in atleast one subject. So it's very strategic and important role of optional subject in UPSC exam.