Step 1: Recall the relation between electric and magnetic fields in an electromagnetic wave.
For an electromagnetic wave in vacuum,
\[
E_0=cB_0
\]
where
\[
c=\text{speed of light}
\]
Step 2: Write the relation between angular frequency and wave number.
For a wave,
\[
c=\frac{\omega}{k}
\]
where
\[
\omega=\text{angular frequency}
\]
and
\[
k=\text{wave number}
\]
Step 3: Substitute the value of \(c\).
Using
\[
E_0=cB_0
\]
we get
\[
E_0=\frac{\omega}{k}B_0
\]
Multiplying both sides by \(k\),
\[
E_0k=B_0\omega
\]
Step 4: Final conclusion.
Hence, the correct relation is
\[
\boxed{E_0k=B_0\omega}
\]