A shell flying along a parabolic path explodes in mid-air into several fragments. Air resistance is negligible. Consider statements I to IV and select the option that names every correct statement and no incorrect one.

• I. The centre of mass of the fragments continues along the original parabola until a fragment hits the ground.
• II. The total momentum of the fragments just after the explosion equals the shell's momentum just before.
• III. The total kinetic energy of the fragments just after the explosion equals the shell's kinetic energy just before.
• IV. The forces of the explosion can change the velocity of the centre of mass.