divide 12 radical 15/3 give an exact answer please

To simplify the expression \(\frac{12 \sqrt{15}}{3}\), we can divide the coefficients first:

\[ \frac{12}{3} = 4 \]

Now, the expression becomes:

\[ 4 \sqrt{15} \]

Therefore, the exact answer is:

C. \(4 \sqrt{15}\)