Darius started his baseball card collection with 7 cards that he got from his dad. He bought 1 pack of cards each month for 20 years. After 1 year he had 79 cards in his collection. Darius gave his entire collection to his son 20 years after he got it from his dad. Which of the following is the domain of the function representing the number of baseball cards in Darius’s collection?
A. 7< or = x< or = 1,580
B.7< or = x< or = 1,447
C.0< or = x
D.0< or = x< or = 20