A torque of $20\; Nm$ acting on a rigid body produces are angular acceleration of $4 rad /s^2$ What is the moment of inertia of the rigid body rotating about the fixed axis?

Question

$$\begin {array} {1 1} (a)\;5\;kg\;m^2 & \quad (b)\;4\;kg\;m^2 \\ (c)\;80\;kg\;m^2 & \quad  (d)\;12\;kg\;m^2 \end {array}$$