**A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of θ, where θ is the angle by which is has rotated, is given as kθ2 . If its moment of inertia is I then the angular acceleration of the disc is**

** (1) k/I θ (2) k/2I θ (3) k/4I θ (4) 2k/I θ**