It's the pricing of the product

Single product pricing refers to a single purchase, such as one bottle of Pepsi. Multiple product pricing refers to purchasing more than one product at a time, such as a pallet of Pepsi.

Explain how product form pricing may be pricing option at Quills?

Cost plus pricing is based on full product cost plus desired profit margin to arrive at the product price, while marginal cost plus pricing makes use of the product's total variable cost plus desired profit margin to arrive at the product's price. Marginal cost plus pricing (or "mark-up pricing) is based on demand, and completely ignores fixed costs in arriving at the product's price.