Keeping in view that; a block is attached to the end of an ideal spring & moved from coordinate Xi to xf the relaxed position is at x=0.
The work done by spring is positive if xi =−4cm and xf =−2cm
This is because the spring is relaxed at x=0 , therefore in all options apart from "xi =−4cm and xf =−2cm " the spring is either compressed or stretched and is moving towards a more strained position respectively. This shows that work is done on the spring or work done by the spring is negative.
Yet when, xi =−4cm and xf =−2cm the spring is going from stretched/compressed state to relaxed therefore work done by spring is positive.
