The tables show the cost of different numbers of t-shirts ordered at two different stores, Store C and Store D: Store C

Number
of T-shirtsCost (in $)
2$12
4$24
8$48

Store D

Number
of T-shirtsCost (in $)
3$21
6$42
9$63

Which of these explains which store has a better buy?
Store C, because the ratio of the number to the cost is 6:1 in Store C and 7:1 in Store D.
Store C, because the ratio of the number to the cost is 1:6 in Store C and 1:7 in Store D.
Store D, because the ratio of the number to the cost is 2:14 in Store C and 3:24 in Store D.
Store D, because the ratio of the number to the cost is 14:2 in Store C and 24:3 in Store D.