A circular \( \operatorname{disc} D_{1} \) of mass \( M \) and radi...

A circular \( \operatorname{disc} D_{1} \) of mass \( M \) and radius \( R \) has two identical discs \( D_{2} \) and \( D_{3} \) of the same mass \( M \) and radius \( R \) attached rigidly at its opposite ends (see figure). The moment of inertia of the system about the axis \( O O^{\prime} \) passing through the centre of \( D_{1} \), as shown in the figure will be
(2019 Main, 11 Jan II)
(a) \( \frac{2}{3} M R^{2} \)
(b) \( \frac{4}{5} M R^{2} \)
(c) \( 3 M R^{2} \)
(d) \( M R^{2} \)