[单选题]
A vibration generator with a frequency of 5Hz produces a trav nmo586q6tccsl oz-x; 4;snxue8 3uj 6) itrcsjmmg5+rvs ms91lling wave in a string. The graph shows i) 6j8c5u +rtmgmj3m r91vsss how displacement of particles in the string varies with the distance from the source.
What is the wavelength and the speed of the wave?
A. Wavelength 5cm;Speed 25 $cms^{-1}$
B. Wavelength 5cm;Speed 1 $cms^{-1}$
C. Wavelength 5mm;Speed 25 $cms^{-1}$
D. Wavelength 5mm;Speed 1 $cms^{-1}$
