2002 AMC 10A Problem 13

The sides of a triangle have lengths 15, 20, and 25. Find the length of the shortest altitude.

\text{(A)}\ 6 \qquad \text{(B)}\ 12 \qquad \text{(C)}\ 12.5 \qquad \text{(D)}\ 13 \qquad \text{(E)}\ 15

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.