AHSME 1993 Problem 13

A square of perimeter 20 is inscribed in a square of perimeter 28. What is the greatest distance between a vertex of the inner square and a vertex of the outer square? $\text{(A) } \sqrt{58} \text{(B) } \frac{7\sqrt{5}}{2} \text{(C) } 8 \text{(D) } \sqrt{65} \text{(E) } 5\sqrt{3}$