(a) angular momentum
(b) linear momentum
Explanation:
If L be the angular momentum, then external torque = dL/dt
But given that it is zero, so dL/dt =0
→L = a constant.
Similarly, it can be shown that linear momentum = a constant.
(c) is not correct because in such situation total energy is constant.
(d) is not correct because the moment of Inertia does not depend upon the external force, it depends upon the shape and the axis of rotation. In a nonrigid body, these two may not remain constant.
