Two points of a rod move with velocities 3v and v perpendicular to the rod and in the same direction, separated by a distance r. then the angular velocity of the rod is

• A

  $\frac{3\mathrm{v}}{\mathrm{r}}$

• B

  $\frac{4\mathrm{v}}{\mathrm{r}}$

• C

  $\frac{5\mathrm{v}}{\mathrm{r}}$

• D

  $\frac{2\mathrm{v}}{\mathrm{r}}$