Answer
(B) $108\;km/h$.
Work Step by Step
Convert units:
$\Rightarrow 1\;m/s=3.6\;km/h$
Multiply both sides by $30$.
$\Rightarrow 30\cdot 1\;m/s=30\cdot 3.6\;km/h$
Simplify.
$\Rightarrow 30\;m/s=108\;km/h$
Hence, the correct option is (B) $108\;km/h$.