The total cost of gasoline varies directly with the number of gallons purchased. Kathy pays $17.93 for 11
gallons of gasoline. Which equation shows the relationship between the total cost of gasoline, c, and the
number of gallons purchased, n?

A. n = 17.93c
B. c = 17.98n
C. n = 1.63c
D. c = 1.63n