A frustum is formed when a plane parallel to a cone’s base cuts off the upper portion as shown. A cone is shown. The top of the cone is cut off to form a frustum of the bottom portion. The cone has a radius of 3. 5 and a height of 8. The frustum has a height of 11 and a radius of 7. 5. Which expression represents the volume, in cubic units, of the frustum? One-thirdĎ€(7. 52)(11) â€" One-thirdĎ€(3. 52)(8) One-thirdĎ€(7. 52)(11) One-thirdĎ€(3. 52)(8) One-thirdĎ€(7. 52)(19) â€" One-thirdĎ€(3. 52)(8) One-thirdĎ€(7. 52)(19) One-thirdĎ€(3. 52)(8).