For a number to be divisible by 99, it must be divisible by 9 and 11 (A) : 51579 = 5 + 1 + 5 + 7 + 9 = 27 which is divisible by 9 and also by 11 (B) : 51557 = 5 + 1 + 5 + 5 + 7 = 23 which is not divisible by 9 (C) : 55036 = 5 + 5 + 0 + 3 + 6 = 19 which is not divisible by 9 (D) : 49984 = 4 + 9 + 9 + 8 + 4 = 34 which is not divisible by 9 Thus, only option (A) is divisible by 99