The correct answer is D. One factor is rational, but the other is irrational.
The square root of 225 (√225) can be written as 15. 15 is a rational number since it can be expressed as a fraction (15/1). Therefore, one factor is rational.
The other factor can be found by dividing 225 by 15, which equals 15. 15 is not a rational number because it cannot be expressed as a fraction, so it is an irrational number. Therefore, the other factor is irrational.