In the figure, a semicircle with center A and radius $[AC]$ and a semicircle with center B and radius $[BC]$ are given. Point B is on the circle centered at A, and point A is on the circle centered at B.
Accordingly, what is the area of the shaded region in square units?\\
A) $36\pi$\\
B) $42\pi$\\
C) $48\pi$\\
D) $54\pi$\\
E) $60\pi$