Let $\overrightarrow{\mathrm{F}}$ be the force acting on particle having position vector $\overrightarrow{\mathrm{r}}$ and $\overrightarrow{\mathrm{\tau }}$ be. the torque of this force about the origin. Then :

• A

  $\overrightarrow{\mathrm{r}}\cdot \overrightarrow{\mathrm{\tau }}=0 \mathrm{and} \overrightarrow{\mathrm{F}}\cdot \overrightarrow{\mathrm{\tau }}\ne 0$

• B

  $\overrightarrow{\mathrm{r}}\cdot \overrightarrow{\mathrm{\tau }}\ne 0 and \overrightarrow{\mathrm{F}}\cdot \overrightarrow{\mathrm{\tau }}=0$

• C

  $\overrightarrow{\mathrm{r}}\cdot \overrightarrow{\mathrm{\tau }}\ne 0\text{ and }\overrightarrow{\mathrm{F}}\cdot \overrightarrow{\mathrm{\tau }}\ne 0$

• D

  $\overrightarrow{\mathrm{r}}\cdot \overrightarrow{\mathrm{\tau }}=0\text{ and }\overrightarrow{\mathrm{F}}\cdot \overrightarrow{\mathrm{\tau }}=0$