Correct Answer - B
Let the equation of wave by `y=A sin (omega t-kx)`
where, `omega=2pi n` and `k=(2pi)/lambda`.
Wave velocity, `V=n lambda =omega /(2pi)xx(2pi)/k=omega/k`
Maximum particle velocity `v= A omega`
For `V=v, omega/k=A omega` or `A=1/k=lambda/(2pi)`.