In the addition problem shown, m, n, p, and q represent positive digits. When the problem is completed correctly, the value of m+n+p+q is
\begin{array}{rrrrr}
&&n &6&3 \\
&&7 &p &2 \\
+&& 5&8 &q \\
\hline &m& 0&4&2
\end{array}
Answer Choices
A. 23
B. 24
C. 21
D. 22
E. 20