A Karate Master Strikes a Board with an Initial Velocity

Multiple Choice

A karate master strikes a board with an initial velocity of 12.0 m/s,decreasing to 3.0 m/s as his hand passes through the board.If the time of contact with the board is 0.002 s,and the mass of the coordinated hand and arm is 1.0 kg,what is the force exerted on the board?

A) 7.5E+3 N
B) 1.8E-2 N
C) 3.0E-2 N
D) 4.5E+3 N
E) 6.0E+3 N