An electromagnetic wave with angular frequency $\omega$ and wavelength $\lambda$ propagates in the $+y$ direction. Its magnetic field is directed along the $-x$ direction. The vector expression for the associated electric field (with amplitude $E_0$) is ...........

• A
  $\vec E = E_0 \cos \left( \omega t - \frac{2\pi}{\lambda} y \right) \hat x$
• B
  $\vec E = -E_0 \cos \left( \omega t + \frac{2\pi}{\lambda} y \right) \hat x$
• C
  $\vec E = -E_0 \cos \left( \omega t + \frac{2\pi}{\lambda} y \right) \hat z$
• D
  $\vec E = E_0 \cos \left( \omega t - \frac{2\pi}{\lambda} y \right) \hat z$