[单选题]
A vibration generator with a /) s mh3jlih *s*lg4cdfrequency of 5Hz produces a travelling wave inpxq-)q b zn7g)6*/cerb2xflhg6a4 j4*aav oa a string. The gf 7cxh lvjban r-4a4a*xz qq)2 *bg/)6epao 6graph shows 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 $cms^{-1}$
