11 Given the radius of a sphere is 2, and the planes of three great circles on the sphere are mutually perpendicular, then the volume of the octahedron formed by the intersection points of the three great circles is ( ).
(A) $\frac{16}{3}$
(B) $\frac{32}{3}$
(C) $\frac{64}{3}$
(D) 32
$11 \mathrm{~B}$