Given:
The volume of a cylinder is 
 cubic units.
A cone shares the same base.
The height of the cone is twice the height of the cylinder.
We need to determine the volume of the cone.
Height of the Cone:
Let h denote the height of the cylinder.
Let H denote the height of the cone.
Since, it is given that, the height of the cone is twice the height of the cylinder, we have;

Volume of the cylinder:
The formula to determine the volume of the cylinder is 

Since, volume of the cylinder is 
, we get;
 -------(1)
Volume of the cone:
The formula to determine the volume of the cone is 

Substituting 
, we get;


Substituting equation (1), we get;


Thus, the volume of the cone is 20π
Hence, Option C is the correct answer.