A tape of length l and weight w kg/m is suspended at its ends with a pull of p kg, the sag correction is:

A

$$\frac{l^2w^2}{24p^2}$$

B

$$\frac{l^2w^3}{24p^2}$$

C

$$\frac{lw^2}{24p}$$

D

$$\frac{l^2w^2}{24p^3}$$