$A$ uniform capillary tube of length $l$ and inner radius $r$ with its upper end sealed is submerged vertically into water. The outside pressure is $p_{0}$ and surface tension of water is $\gamma$. When a length $x$ of the capillary is submerged into water, it is found that water levels inside and outside the capillary coincide. The value of $x$ is

• A
  $\frac{l}{\left(1+\frac{p_{0} r}{4 \gamma}\right)}$
• B
  $l\left(1-\frac{p_{0} r}{4 \gamma}\right)$
• C
  $l\left(1-\frac{p_{0} r}{2 \gamma}\right)$
• D
  $\frac{l}{\left(1+\frac{p_{0} r}{2 \gamma}\right)}$