A wave $y = a\sin(\omega t - kx)$ on a string meets with another wave producing a node at $x = 0$. Then the equation of the unknown wave is\\
(1) $y = a\sin(\omega t + kx)$\\
(2) $y = -a\sin(\omega t + kx)$\\
(3) $y = a\sin(\omega t - kx)$\\
(4) $y = -a\sin(\omega t - kx)$