Thee spheres each of mass M and radius R are placed in contact with each other as shown in the figure here. Then the moment of inertia of the system about the axis CC' is

Three discs each of mass M and radius R are placed in contact with each other as shown in figure here. Then the MI of the system about an axis XX' is

Three rings each of mass M and radius R are placed in contact with each other as shown . Then MI of the system about YY' axis is

Three identical spheres each of mass M and radius R are arranged in a row touching each other and their centres collinear.The moment of inertia of the system about an axis passing through the centre of the middle sphere and perpendicular to the line joining their centres is "