Correct Answer - D
We know that,
`k=(2pi)/(100)`
or `(2pi)/(lambda)=(2pi)/(100)`
`therefore " "lambda = 100 cm`
But `v_("Particle")=(del y)/(del t) = a omega cos (omega t - kx)`
`(v_("Particle"))_("max")= a omega = 4 xx (2pi)/(0.02)=400 pi cm//s`
`therefore " "(v_("Particle"))_("max")/(lambda)=(400 pi)/(100)= 4pi`