The gas mileage of car a is 21 miles per gallon. the gas mileage of car b is 30 miles per gallon. which of the following graphs would represent this data most accurately?

a. a pictograph shows two squares. one square has a side length of 11, and the other has a side length of 15.

b. the y-axis of a bar graph starts at zero gallons. one bar is 22 units, and the other bar is 30 units.

c. a pictograph shows two cubes. one cube has a side length of 7, and the other has a side length of 10.

d. the y-axis of a bar graph starts at 20 gallons. one bar is 22 units, and the other bar is 30 units.