A disc is rolling without slipping on a surface. The radius of the disc is $R.$ At $t=0,$ the top most point on the disc is $A$ as shown in figure. When the disc completes half of its rotation, the displacement of point $A$ from its initial position is

• A

  $2R$
• Correct answer
  B

  $R\sqrt{\left({\pi }^2+4\right)}$
• C

  $\mathrm{R}\sqrt{\left({\pi }^2+1\right)}$
• D

  $2R\sqrt{\left(1+4{\pi }^2\right)}$

Hence, the correct answer is option: 'B'.