Secret Sneaker will give anyone $10 for an old pair of sneakers, regardless of condition, when that person purchases a new pair of sneakers. The end result is essentially reducing the price of the new sneakers by $10. What is this type of price adjustment called?
A) functional discount
B) captive product
C) seasonal discount
D) trade-in allowance
E) by-product
Answer: D) trade-in allowance