Two Traveling Waves, Y₁ = a Sin[k(x - Vt)] and Y₂

Multiple Choice

Two traveling waves, y₁ = A sin[k(x - vt) ] and y₂ = A sin[k(x + vt) ], are superposed on the same string.The distance between the adjacent nodes is:

A) "vt/ $\pi$ "
B) "vt/2 $\pi$ "
C) " $\pi$ /2k"
D) " $\pi$ /k"
E) "2 $\pi$ /k"