What is the formula for elongation of a conical bar (with length L and self weight W) due toits self weight?

A

$$\frac{WL}{2A_{min}E}$$

B

$$\frac{WL^2}{2A_{min}E}$$

C

$$\frac{WL}{2A_{max}E}$$

D

$$\frac{WL^2}{2A_{max}E}$$