A family of four went to dinner at a local restaurant. Three of the family members ordered the special dinner that costs $12.88 each and the fourth family member ordered the hamburger and fries combo that costs $6.78. If they want to leave a 15% tip, which of the following expressions represents the amount of tip they should leave? A. (12.88+6.78)×0.15

B. (3×12.88+6.78)×0.15

C. 3×12.88+6.78

D. [3×(12.88+6.78)]×0.15