Two guitar strings are subjected to tensile forces. String X experiences a tensile force $F$, producing an extension $x$. String Y experiences a tensile force $2F$, producing an extension $2x$. The strings follow Hooke’s law. What is the ratio $\frac{\text{strain energy in stretched string X}}{\text{strain energy in stretched string Y}}$?
- A$4$
- B$2$
- C$\frac{1}{2}$
- D$\frac{1}{4}$