A 1,600 kg train car rolling freely on level track at 16 m/s bumps into a 1.0 × 103 kg train car moving at 10.0 m/s in the same direction, and the two latch onto each other and continue together. What is their final speed?

A.) 16 m/s
B.) 6.0 m/s
C.) 10 m/s
D.) 14 m/s