In the figure below the small circle is inscribed in a square, which is inscribed in the large circle. What is the ratio of the area of the large circle to that of the small circle.

Question

$\begin{array}{1 1} (a)\; \sqrt{2}:1 \\ (b)\; 1 : \sqrt{2} \\ (c)\; 2:1 \\ (d)\; 1:2 \end{array}$