Step 1: Classify the numbers. The provided options are all perfect squares: \[ 121 = 11^2,\quad 144 = 12^2,\quad 169 = 13^2,\quad 225 = 15^2 \] Step 2: Examine the bases of the squares.
The bases 11, 13, and 15 are odd numbers.
The base 12 is an even number.
Step 3: Determine the outlier. Only 144 is the square of an even number. The remaining numbers are squares of odd numbers.
Conclusion: The number that is distinct from the rest is: 144