You have to look at the y-axis (or subtract the y numbers ex 34-12=22 which is how we know A is going up by 22 per hour)
A is going up by 22 every 1 hour.
B is going up by 36/2=18 every 1 hour.
C is going up by 34/2=17 every 1 hour.
D is going up by 32/2=16 every 1 hour.
The answer is A. It's traveling the most distance in miles per hour.