Electromagnetic Waves: JEE Main 2021 Physics question

A plane electromagnetic wave of frequency 100 MHz is travelling in vacuum along the x-direction. At a particular point in space and time, $\overrightarrow B = 2.0 \times {10^{ - 8}}\widehat kT$. (where, $\widehat k$ is unit vector along z-direction) What is $\overrightarrow E$ at this point?