A juice bar sells 530 1-L jugs of fruit juice per day at a price of $4. 20. The previous year sales have revealed that for every $0. 10 increase in price, the store will sell 5 fewer 1-L jugs. What is the selling price that would give the maximum profit?
a) $4. 10
b) $4. 20
c) $4. 30
d) $4. 40
