In the diagram, a wire with diameter $D$ and length $L$ is held tightly at one end between two blocks of wood. A load is then placed on the wire, making it increase in length by $x$. If the same load is applied to a wire of the same material with diameter $2D$ and length $3L$, what extension would it produce?
- A$\frac{2}{3}x$
- B$\frac{3}{4}x$
- C$\frac{4}{3}x$
- D$\frac{3}{2}x$