Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The kinetic energy needed to project a body of mass $m$ from the Earth's surface to infinity is $\frac{1}{2} mgR$,where $R$ is the radius of the Earth.
Reason $R$: The maximum potential energy of a body is zero when it is projected to infinity from the Earth's surface.
In the light of the above statements,choose the correct answer from the options given below.

• A
  $A$ is false but $R$ is true.
• B
  Both $A$ and $R$ are true and $R$ is the correct explanation of $A$.
• C
  $A$ is true but $R$ is false.
• D
  Both $A$ and $R$ are true but $R$ is $\text{NOT}$ the correct explanation of $A$.