UPSC 2015 CDS I English Paper

The given context implies that every player here should have a knowledge of or be competent in the rules of game. Hence, the preposition ‘at’ needs to be replaced with the preposition ‘with’ as ‘conversant’ takes the preposition ‘with’ and the phrase ‘conversant with’ together means ‘to have knowledge of/be competent in’. Thus, option (c) is correct.