A 3.00 m long, 30.0 kg uniform ice raft is initially at rest on a frictionless horizontal surface. A 70.0 kg person walks from one end of the raft to the other at a constant speed of 3.00 m/s relative to the surface. What is the speed of the raft with respect to the surface while the person is walking?
A) 1.50 m/s
B) 2.10 m/s
C) 3.00 m/s
D) 4.20 m/s