Pick up the correct statement from the following :

• If two equal and perfectly elastic smooth spheres impinge directly, they interchange their velocities.
• If a sphere impinges directly on an equal sphere which is at rest, then a fraction (1 - e2) the original kinetic energy is lost by the impact.
• If a smooth sphere impinges on another sphere, which is at rest, the latter will move along the line of centres.
• If two equal spheres which are perfectly elastic impinge at right angles, their direction after impact will still be at right angles.
• All the above.