A tent is in the form of a cylinder surmounted by a cone. The radius of the base of the cylinder is 30 feet and its height is 10 feet. If the total height of the tent is 20 feet, then the volume enclosed by the tent (in cubic feet) is

A

$$120 \pi$$

B

$$1200 \pi$$

C

$$12000 \pi$$

D

$$140 \pi$$