Which of the following word problems can be solved using the equation 12 ÷ 4 = a?

A. There are twelve cookies in a dozen. If a dozen cookies are shared equally among four children, how many cookies does each child get? Let a represent the number of cookies that each child gets.
B. There are 12 buttons on each band uniform. How many buttons are on four band uniforms? Let a represent the total number of buttons.
C. There is twelve boats racing on the Colorado River. If four boats are taken out of the race, how many boats are left? Let a represent the number of boats left.
D. If four monkeys are brought to the city zoo, and 12 monkeys already live at the zoo, how many monkeys will there be altogether? Let a represent the total number of monkeys.