In Vacuum, the Components of An $\mathrm{EM}$ Wave Are , And $\mathrm{E}_{\mathrm{z}}=0$

In vacuum, the components of an $\mathrm{EM}$ wave are $\mathrm{E}_{\mathrm{y}}=(50 \mathrm{~V} / \mathrm{m}) \cos \left[\left(5.00 \mathrm{~m}^{-1}\right) \mathrm{x}+\omega \mathrm{t}\right], \mathrm{E}_{\mathrm{x}}=0$ , and $\mathrm{E}_{\mathrm{z}}=0$ . What is $\omega$ ?

A) $1.00 \times 10^{9} \mathrm{rad} / \mathrm{s}$
B) $1.50 \times 10^{9} \mathrm{rad} / \mathrm{s}$
C) $8.00 \times 10^{8} \mathrm{rad} / \mathrm{s}$
D) $1.20 \times 10^{9} \mathrm{rad} / \mathrm{s}$
E) More information is needed.