AMC8 2006 Problem 24

In the multiplication problem below, A, B, C and D are different digits. What is A+B?

\begin{array}{cccc} & A & B & A \\ \times & C & D & \\ \hline C & D & C & D \\ \end{array}

Answer Choices
A. 1
B. 2
C. 3
D. 4
E. 9