Explanation:
The wave propagates with \(v\) along \( + x\) direction along the direction of pointing vector \(\overrightarrow S \)
\(\overrightarrow S = \frac{{\vec E \times \vec B}}{{{\mu _0}}}\,\,\,\,\,\,\,\,\left[ {{\rm{given}}\,\overrightarrow E \,{\mathop{\rm is}\nolimits} \,{\rm{along}}\, + y} \right]\)
\(B\) will be along \( + z\).