An Indian rubber cord L metre long and area of cross-section A\[metr{{e}^{2}}\] is suspended vertically. Density of rubber is D \[kg/metr{{e}^{3}}\] and Young's modulus of rubber is E \[newton/metr{{e}^{2}}\]. If the wire extends by l metre under its own weight, then extension l is

• A.             \[{{L}^{2}}Dg/E\]
• B.               \[{{L}^{2}}Dg/2E\]
• C.             \[{{L}^{2}}Dg/4E\]
• D.               L