(A) : A spring has potential energy, both when it is compressed or stretched.
(R) : In compressing or stretching, work is done on the spring against the restoring force.

Potential energy = $\frac{1}{2}{\mathrm{kx}}^2$

When a string is compressed, x becomes positive while it is stretched. In either scenario, spring will attempt to reshape itself to its original form. Therefore, the work against its restoring force is represented by this Potential Energy.

Hence the correct answer is Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation of ‘A’ .