Two resistors $R_1$ and $R_2$ are constructed from wire of the same material. They are joined in parallel in a circuit, as shown. The diameter of $R_2$ is half that of $R_1$. The resistance of $R_2$ is three times that of $R_1$. What is the value of the ratio $\dfrac{\text{average drift speed of free electrons in } R_1}{\text{average drift speed of free electrons in } R_2}$?
- A$\frac{3}{2}$
- B$\frac{3}{4}$
- C$\frac{1}{6}$
- D$\frac{1}{12}$