Assertion $(A)$: The scalar product of force $\vec{F}$ and displacement $\vec{r}$ is equal to the work done.
Reason $(R)$: The work done is not a scalar quantity.

• A
  $A$ and $R$ are both independently true and $R$ is the correct explanation for $A$.
• B
  $A$ and $R$ are both independently true and $R$ is not the correct explanation for $A$.
• C
  $A$ is true but $R$ is false.
• D
  $A$ is false but $R$ is true.