To convert the speed from meters per second (m/s) to kilometers per hour (km/h), you can use the following conversion:

\[
\text{Speed in km/h} = \text{Speed in m/s} \times \frac{18}{5}
\]

Given:
\[
\text{Speed} = 200 \, \text{m/s}
\]

Now, convert it to km/h:
\[
\text{Speed in km/h} = 200 \times \frac{18}{5} = 200 \times 3.6 = 720 \, \text{km/h}
\]

So, the speed of the aeroplane in kilometers per hour is 720 km/hr.

The correct answer is B. 720 km/hr.