Answer:
A. Coupon.
Explanation:
A coupon is a ticket that has financial value when redeemed. A coupon is sometimes  put as a free gift inside a product.
It is usually used as an advert strategy to get people to buy more products because if consumers know that they are likely to find a coupon inside each product of a particular brand they purchase, it will theoretically lead to more people buying the product in order to get the coupon.
This was the strategy used by Cracker Jack who sold brand snacks of caramel coated popcorn as it had a free prize inside every box which in turn made the product to become immensely popular.
