A 13-ounce box of cereal sells for $3.25. An 18-ounce box of cereal sells for $3.60. Which statement describes the difference in the unit prices of the two boxes of cereal?
A. The 13-ounce box is 5 cents cheaper per ounce.
B. The 13-ounce box is 7 cents cheaper per ounce.
C. The 18-ounce box is 5 cents cheaper per ounce.
D. The 18-ounce box is 7 cents cheaper per ounce.