A wire obeys Hooks law is of length 11 when it is in equilibrium under a tension F1. Its length becomes 12 when the tension is increased to F2. The energy stored in the wire during this process is____________________?
(A) (F1+F2) (121+122)
(B) (F1+F2) (122-112)
(C) (F1+F2) (12-11)
(D) (F1+F2) (12-11)

