Plane X flies at r miles per hour from A to B. Plane Y flies

I get E

You have D (doesn't really matter what the distance is) - you can assume a distance - let's call it 300 miles. What we need to answer is which plane is flying at a faster rate. In order to answer this we need to know T:

1) doesn't give us anything about T

2) doesn't tell us anything useful - City C can be closer to A or B - we don't know.

Combine these two statements we get City C is closer to A and Plane X flies over City C before Plane Y. Doesn't tell us anything - because Plane X can be flying 100 mph and plane Y can be flying 150 mph and if the cities are 300 miles away from one another - depending on where city C is Plane X can reach city C before plane Y. Vice Versa - Plane Y can be flying at 150 mph and Plane X can be flying at Mach 2.5 and plane x would of course pass city C before plane y. You can have different outcomes when combined thus Answer E.