The speed of electromagnetic waves in vacuum is given by

Question

$\begin {array} {1 1} (a)\;\large\frac{1}{\mu_0 \in_0} & \quad (b)\;\large\frac{1}{\sqrt{\mu_0 \in_0}} \\ (c)\;\mu_0 \in_0 & \quad (d)\;\sqrt{\mu_0 \in_0} \end {array}$