The rise or fall of head "h" in a cspillary tube of diameter "d" and liquid syrface tension $$' \sigma '$$ and the specific weight w is equal to

A

$$\frac{4\sigma}{wd}$$

B

$$\frac{4d\sigma}{w}$$

C

$$\frac{4wd}{\sigma}$$

D

$$\frac{4w\sigma}{d}$$