K is the force constant of a spring. The work done is increasing its extension from `l_(1)` to `l_(2)` will be

Options

A. `K = (l_(1) - l_(2))`
B. `(K)/(2)(l_(2) + l_(1))`
C. `K(l_(1)^(2)-l_(1)^(2))`
D. `(K)_(2)(l_(2)^(2)-l_(1)^(2))`

Answer

D