Two identical spherical balls of mass $M$ and radius $R$ each are stuck on two ends of a rod of length $2R$ and mass $M$ (see figure). The moment of inertia of the system about the axis passing perpendicularly through the centre of the rod is\\
(1) $\frac { 209 } { 15 } M R ^ { 2 }$.\\
(2) $\frac { 152 } { 15 } M R ^ { 2 }$.\\
(3) $\frac { 137 } { 15 } M R ^ { 2 }$.\\
(4) $\frac { 17 } { 5 } M R ^ { 2 }$.