Brayden is selling lemonade in glasses that hold of a gallon? If he makes gallons of lemonade, which expression shows how many glasses he can sell?

a. 2 7/8 ÷ 12
b. 1/12 ÷ 2 7/8
c. 2 7/8 ÷ 1/12
d 1/12 ÷ 8/23