Answer:
Option B
Explanation:
Speed of the train relative to man $=\left(\frac{125}{10}\right)$ m/sec $=\left(\frac{25}{2}\right)$ m/sec.
$=\left(\frac{25}{2}\times\frac{18}{5}\right)$ km/hr $=45$ km/hr.
Let the speed of the train be $x$ kmph. Then, relative speed $=(x-5)$ kmph.
$\therefore$ $x-5=45$ or $x=50$ kmph.