The escape velocity from a planet of mass M and radius R is given by :

• A

  $\sqrt{\left(\frac{2\mathrm{GM}}{\mathrm{R}}\right)}$

• B

  $2\sqrt{\left(\frac{\mathrm{GM}}{\mathrm{R}}\right)}$

• C

  $\sqrt{\left(\frac{2\mathrm{MR}}{\mathrm{G}}\right)}$

• D

  $2\sqrt{\left(\frac{\mathrm{R}}{\mathrm{GM}}\right)}$