1996 AHSME Problem 1

The addition below is incorrect. What is the largest digit that can be changed to make the addition correct?

\begin{array}{rr}&\ \texttt{6 4 1}\\ &\texttt{8 5 2}\\ +&\texttt{9 7 3}\\ &\texttt{2 4 5 6}\end{array}

\text{(A)}\ 4\qquad\text{(B)}\ 5\qquad\text{(C)}\ 6\qquad\text{(D)}\ 7\qquad\text{(E)}\ 8

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