The value of the epression is 6 because 6^2 is 36 and since you're substituting m for 3 the value of the denominator is 6 so essentially you are doing the following operation: 6^2/6 --> 36/6=6
All of the other answers share at least one factor they can be divided by (the numerator in all cases). 5/12 however shares no factors and cannot be simplified anymore.
