2: For every gallon of gas purchased, $3.75 was paid.
Step-by-step explanation:
Both options 1 and 3 would require having a dot plotted at those points to be sure, and they're close but they're still approximations. And option 4 is irrelevant. However the point at (4,15) can be used to check option two: 15/4 = 3.75 , ie the price per gallon of gas.
