d
(d) Compare the given equation with
$y = a\sin (\omega t + kx)$
==> $\omega = 2\pi n = 100$
==> $n = \frac{{50}}{\pi }Hz$
$k = \frac{{2\pi }}{\lambda } = 1$
==> $\lambda = 2\pi $ and $v = \omega /k = 100\,m/s$
Since $‘+’$ is given between $t$ terms and $x$ term, so wave is travelling in negative $x-$direction.