A 30-Kg Girl and a 25-Kg Boy Face Each Other

A 30-kg girl and a 25-kg boy face each other on friction-free roller blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girl's speed is

A) 0.45 m/s.
B) 0.55 m/s.
C) 0.83 m/s.
D) 1.2 m/s.