Final answer:
The manufacturer is using the promotion tool of samples by including a trial size of smoothing hair gel with their shampoo and conditioner product to encourage consumers to try new items. The correct option is option (b).
Step-by-step explanation:
The two-in-one combination shampoo and conditioner that is being shrink-wrapped with a 4-ounce foil packet of smoothing hair gel is using the promotion tool of samples.
This marketing strategy provides a trial size of a product so that consumers can try the item before committing to a full-size purchase. It can increase brand awareness and introduce consumers to a new product with minimal risk. This is different from offering rebates, coupons, or price packs, as those are generally monetary incentives whereas samples are a physical trial of the product.