13. (12 points) The students went boating together, but there were not enough boats in the park. If each boat carried 4 people, there would be 10 people left over; if each boat carried 5 people, there would still be 1 person left over. There are ( ) people going boating.
A. 36
B. 46
C. 51
D. 52
【Answer】Solution: $(10-1) \div(5-4)$
$$
\begin{array}{l}
=9 \div 1 \\
=9 \text { (boats) } \\
4 \times 9+10 \\
=36+10 \\
=46 \text { (people) }
\end{array}
$$

Answer: A total of 46 people went boating.
Therefore, the correct choice is: B.