A small coffee shop sells bags of two types of coffee. Bag A contains 24 ounces and costs $15.60. Bag B contains 30 ounces and costs $20.40. Which statement is true?
A: Bag A costs 3g less per ounce than Bag B. B: Bag A costs 3g more per ounce than Bag B.
C: Bag A costs 2 less per ounce than Bag B.
D: Bag A costs 2 more per ounce than Bag B.