As I chose medical science as my optional in upsc , was skeptical about the study materials available for the same. Even it was available especially Previous year question papers , it used to be unsolved . But Dr Chetan Singh's 12 years solved papers came as a life saver..must say this. The presentation is quite crisp and worth !!! the diagrams , flowcharts and all incorporated on point. On questions that all the questions got repeated over years are highlighted. For upsc aspirants who took...