Base cannot be 9 or 8 because largest digit in given question is 9 then base must be >9. Hence, option a and b is eliminated.
Now check for option c, if base 10, 93/4=23.25 but in question 93/4=23 is given, this option is also eliminated.
Now only one option is left, Lets check for Base 11,
9x11¹+3x11⁰= 99+3=102 (in decimal), 4x11⁰=4 (in decimal), 2x11¹+3x11⁰=25 (in decimal). 102/4=25.5 which is equal to 23.555….(base11). which is also not equal to 23. This option is also eliminated. Hence no option is correct