Moment of inertia of a portion of a disc about an axis perpendicular to its plane; Mass of the object is M and radius R is

Question

\[\begin {array} {1 1} (a)\;\frac{MR^2}{2} & \quad (b)\;\frac{1}{6}\frac{MR^2}{2} \\ (c)\;6.\frac{MR^2}{2} & \quad  (d)\;none\;of\;the \;above \end {array}\]