1955 AHSME Problem 15

The ratio of the areas of two concentric circles is 1: 3. If the radius of the smaller is r, then the difference between the radii is best approximated by:

\textbf{(A)}\ 0.41r \qquad \textbf{(B)}\ 0.73 \qquad \textbf{(C)}\ 0.75 \qquad \textbf{(D)}\ 0.73r \qquad \textbf{(E)}\ 0.75r

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