A box of cereal can be purchased in the large size, which is 15 ounces for $3.14, or the family size, which is 24 ounces for $5.34. Which size box of cereal has the lowest price per ounce, and what is the amount?

a -Large size at $0.21 per ounce
b-Large size at $0.22 per ounce
c-Family size at $0.21 per ounce
d-Family size at $0.22 per ounce