A block attached to a spring, pulled by a constant horizontal force...

A block attached to a spring, pulled by a constant horizontal force, is kept on a smooth surface as shown in the figure. Initially, the spring is in the natural state. Then the maximum positive work that the applied force \( \mathrm{F} \) can do is : [Given that spring does not break]
\( \mathrm{P} \)
(A) \( \frac{F}{K} \)
(B) \( \frac{2 \mathrm{~F}^{2}}{\mathrm{~K}} \)
(C) \( \infty \)
(D) \( \frac{F_{2}}{2 \mathrm{~K}} \)