Two Identical 5000-Kg Bulldozers Roll Toward Each Other on a Level

Two identical 5000-kg bulldozers roll toward each other on a level road without friction (one at 1 m/s,the other at 2 m/s) Just before they collide,one has a kinetic energy of 2500 J and the other 10,000 J.At this instant their total kinetic energy is

A) 1250 J.
B) 2500 J.
C) 7500 J.
D) 10,000 J.
E) 12,500 J.