Two identical circles intersect so that their centers, and the points at which they intersect, form a square of side 1 cm. The area (in sq. cm) of the portion that is common to the circles is

• A. \(\dfrac{\pi}{4}\)
• B. \(\dfrac{\pi}{2}-1\)
• C. \(\dfrac{\pi}{5}\)
• D. \(\sqrt{2}-1\)