The product of a multiplication problem is 225−−−√

To determine the nature of the factors in the multiplication problem where the product is \( \sqrt{225} \), we first simplify the product:

\[
\sqrt{225} = 15
\]

The number 15 is a rational number. When considering the factors of a rational number, we can conclude:

1. **Both factors can be rational.** For example, \( 1 \times 15 = 15 \) and both 1 and 15 are rational.
2. **One factor can be irrational while the other is rational.** For example, \( \sqrt{2} \times 7.5 = 15 \), where \( \sqrt{2} \) is irrational and \( 7.5 \) is rational.

However, in the case of the product being 15 (a rational number), it is also possible that both factors could be rational.

Thus, the best conclusion is:

**They are both rational because the product is rational.**