The equation of a wave of amplitude 0.02 m and period 0.04 s travelling along a stretched string with a velocity of 25m/s will be
A. ` y= 0.02 sin 2pi (0.04t -0.5x)`
B. ` y= 0.02 sin 2pi (25t -2x) `
C. ` y=0.02sin 2pi (0.04t-x) `
D. ` y= 0.02sin 2pi (25t -x)`
