Two Satellites with Equal Rest Masses of 100 Kg Are

Multiple Choice

Two satellites with equal rest masses of 100 kg are traveling toward each other in deep space. One is traveling at 0.650c and the other at 0.850c. The satellites collide and somehow manage to stick
Together. What is the rest mass of the combined object after the collision?

A) 100 kg
B) 378 kg
C) 312 kg
D) 200 kg
E) 277 kg