11. (10 points) Two cars, A and B, start from points $A$ and $B$ respectively at the same time, heading towards each other, with car A traveling faster than car B. Car A has traveled 60 kilometers when it meets car B at point $C$. After the meeting, car A continues to move forward, while car B turns around and follows the same direction as car A. When car A reaches point $B$, the maximum distance between car A and car B is ( ) kilometers.
A. 10
B. 15
C. 25
D. 30
【Solution】Solution: According to the problem, we have:
Assume that when A travels 60 kilometers, B travels $a$ kilometers. When A reaches point $B$, B should have traveled $\frac{\mathrm{a}}{60} \times \mathrm{a}=\frac{\mathrm{a}^{2}}{60}$ kilometers. At this point, the maximum distance between A and B is $a-\frac{a^{2}}{60}=\frac{a}{60} \times(60-a)$.
Given a constant sum, the smaller the difference, the larger the product, so $60-a=a, a=30$.
The maximum distance between A and B is $30-\frac{900}{60}=15$ (kilometers).
Therefore, the answer is: $B$.