答案：A

解析：

Choice A is correct.

The formula to calculate the volume of a cylinder is Vcylinder=πr^2h where r is the radius and h is the height of the cylinder. The formula to calculate the volume of a sphere is Vsphere=4/3πr^3 where r is the radius of the sphere.

The volume of the clay in the cylinder is π(10^2)(30) and the volume of each sphere is 4/3π6^3. Thus, the number of spheres with a radius of 6 centimeters that the artist will be able to sculpt is the largest integer less than the fraction begin display style fraction π(10^2)(30)/4/3π6^3, which is 10.