Wires X and Y are identical, and each has length $L$ and radius $r$; they are joined in parallel as illustrated. The combined resistance is $R_1$. Wire X is then substituted by a wire of the same material, still of length $L$ but with radius $2r$. The resistance of this revised arrangement is $R_2$. What is the value of the ratio $\frac{R_1}{R_2}$?
- A$\frac{2}{5}$
- B$\frac{2}{3}$
- C$\frac{3}{2}$
- D$\frac{5}{2}$