Answer:
Breaks because it doesn't have force in the radial direction and thus due to inertia the stones will fly off tangentially.
Explanation:
Until the stone is tied to a string, it will possess centripetal force and centrifugal force along the radial direction of motion due to the tension present in the string. Now, when the rope breaks, it breaks because it doesn't have force in the radial direction and thus due to inertia the stones will fly off tangentially.
