2009 AMC 10B Problem 2

Which of the following is equal to \dfrac{\frac{1}{3}-\frac{1}{4}}{\frac{1}{2}-\frac{1}{3}}?

\text{(A) } \frac 14 \qquad \text{(B) } \frac 13 \qquad \text{(C) } \frac 12 \qquad \text{(D) } \frac 23 \qquad \text{(E) } \frac 34

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.