An Unstretched Spring Has a Length of 0

Multiple Choice

An unstretched spring has a length of 0.30 m. When the spring is stretched to a total length of 0.60 m, it supports traveling waves moving at 4.5 m/s. How fast will waves travel on this spring if it is stretched to 0.90 m?

A) 2.3 m/s
B) 4.5 m/s
C) 6.4 m/s
D) 9.0 m/s
E) 10.8 m/s