A 120 Kg Mass, Initially at Rest, Is Blown Apart

Multiple Choice

A 120 kg mass, initially at rest, is blown apart into an 80 kg piece and a 40 kg piece. After the blast, the two masses are moving apart with a relative velocity of 60 m/s. The total kinetic energy after the explosion is

A) 21 kJ.
B) 35 kJ.
C) 48 kJ.
D) 56 kJ.
E) 82 kJ.