The radius of the bore of a capillary tube is r and the angle of contact of the liquid is $\mathrm{\theta }$ . When the tube is dipped in the liquid, the radius of curvature of the meniscus of liquid rising in the tube is

• A

  $\mathrm{r} \mathrm{sin\theta }$

• B

  $\mathrm{r} / \mathrm{sin\theta }$

• C

  $\mathrm{r} \mathrm{cos\theta }$

• D

  $\mathrm{r} / \mathrm{cos\theta }$