An elastic spring of unstretched length `L` and force constant `K` is stretched by amoun t `x` .It is further stretched by another length `y` The work done in the second streaching is
A. `((1)/(2)) ky^(2)`
B. `((1)/(2)) k (x^(2) + y^(2))`
C. `((1)/(2)) k (x + y)^(2)`
D. `((1)/(2)) ky (2 x + y)`
