What is the angle of banking of a railway track of radius of curvature $250 \,m$, if the maximum velocity of the train is $90 \,km/h$? $(g=10 \,ms^{-2})$

• A
  $\theta=\tan^{-1}\left(\frac{1}{2}\right)$
• B
  $\theta=\tan^{-1}\left(\frac{1}{3}\right)$
• C
  $\theta=\tan^{-1}\left(\frac{1}{4}\right)$
• D
  $\theta=\tan^{-1}\left(\frac{1}{5}\right)$