[单选题]
A 2.0-kg mass moves with 0lah x6bgrh78s *z/z xa speed of 5.0 +0dm-lx9r k mdm/s. It collides head-on with a 3.0 kg mass at rest. If the collision is perfectly inelastirlmmx9 - 0kd+dc, what is the speed of the masses after the collision?
A. 10 m/s
B. 2.5 m/s
C. 2.0 m/s
D. 0, since the collision is inelastic
