$A$ glass capillary tube is in the shape of a truncated cone with an apex angle $\alpha$ so that its two ends have cross sections of different radii. When dipped in water vertically,water rises in it to a height $h$,where the radius of its cross section is $b$. If the surface tension of water is $S$,its density is $\rho$,and its contact angle with glass is $\theta$,the value of $h$ will be ($g$ is the acceleration due to gravity).

• A
  $\frac{2 S }{ b \rho g } \cos (\theta-\alpha)$
• B
  $\frac{2 S }{ b \rho g } \cos (\theta+\alpha)$
• C
  $\frac{2 S}{ b \rho g } \cos (\theta-\alpha / 2)$
• D
  $\frac{2 S }{ b \rho g } \cos (\theta+\alpha / 2)$