Which situation represents a proportional relationship?
a. cost of purchasing a basket of oranges for $2.50 per pound plus $8 for the basket
b. the cost of purchasing peaches for $9 per box with the delivery change of $5
c. the cost of purchasing pears for $1.80 per pound with a coupon for $1 off per pound.
d. the cost of purchasing mangoes for $1.25 per
pound plus a shipping fee of $0.16.