Quincy has a bucket that already holds 3 pounds of sand. The bucket is on a scale. Quincy's brother asks him to add sand to the bucket until there are 5 pounds of sand. Quincy adds 5 pounds of sand to the bucket. Quincy most likely needed a better understanding of which of the following?
A that a quantity can be composed of two smaller quantities

B the number facts for sums greater than 10

C the concept of the quantity 5

D one-to-one correspondence between numbers and objects