AMC 8 2007 Problem 21

Two cards are dealt from a deck of four red cards labeled $A$, $B$, $C$, $D$ and four green cards labeled $A$, $B$, $C$, $D$. A winning pair is two of the same color or two of the same letter. What is the probability of drawing a winning pair? $\textbf{(A)}\ \frac{2}{7} \textbf{(B)}\ \frac{3}{8} \textbf{(C)}\ \frac{1}{2} \textbf{(D)}\ \frac{4}{7} \textbf{(E)}\ \frac{5}{8}$