C

    Welcome to Class 4, Grade 7. This is our classroom. There are twenty boys and twenty -four girls in the classroom. The teacher's desk is in the front of the classroom. There is a big blackboard on the front wall and a small blackboard on the back wall. There are two maps on the wall. One is a map of China and the other is a map of the world．There are some photos on the wall. There are some flowers by the windows. Our classroom is very beautiful.

A B C D E 五个景点之间的路线如图所示．若每条路线的里程a(km)及行驶的平均速度b(km/h)用(a,b)表示，则从景点A到景点C用时最少的路线是（　　）