Let's say we have the first toll at distance 0 ,
the next toll at distance greater than 10 ( 10.1 ) ,
the next toll at distance greater than 10 of the last one ( 20.2)
....since the last one is at distance 25 from the first one...the distance from the third and fourth has to be less than 10.
Try other combinations and you will se...
C seems to be the right choice. Please explain.