The Displacement of a Vibrating String Versus Position Along the String

Multiple Choice

The displacement of a vibrating string versus position along the string is shown in the figure.The periodic waves have a speed of 10.0 cm/s.A and B are two points on the string.
-A steel wire of mass 0.400 kg and length 0.640 m supports a 102-kg block.The wire is struck exactly at its midpoint causing a small displacement.How long does it take the peak of this displacement to reach the top of the wire?

A) 2.00 × 10^-3 s
B) 4.00 × 10^-3 s
C) 6.00 × 10^-3 s
D) 8.00 × 10^-3 s
E) 1.60 × 10^-2 s