A sphere of radius R is executing pure rolling on a rough horizontal surface. The acceleration of the point of contact is

• A

  zero

• B

  $\frac{v^2}{R}$ towards the centre

• C

  $\frac{v^2}{R}$ away from the centre

• D

  $\frac{v^2}{R}$ at an angle ${45}^0$ with horizontal direction