A wave $y =a \sin (wt-kx)$ on a string meets with another wave producing a node at $x=0$. Then the equation of the unknown wave is :

Question

( A ) $y = a \sin(wt + kx)$
( B ) $y = a \sin(wt - kx)$
( C ) $y = -a \sin(wt - kx)$
( D ) $y = -a \sin(wt + kx)$