The area (in square units) bounded by the region inside the circle$x^2+y^2=36$  and outside the parabola$y^2=9x$ is

• A

  $24\pi -3\sqrt{3}$

• B

  $24\pi +3\sqrt{3}$

• C

  $36\pi -3\sqrt{3}$

• D

  $36\pi +3\sqrt{3}$