A. A hair care company suggests a line of products to customers based on their hair type, scalp moisture, hair moisture, and whether it is color-treated.

B. Order total is calculated based on the quantity and price of the items in the customer's shopping cart.

C. If customers decide to add insurance, checked bags, or early boarding to their airline tickets, extra fees are added to their order total.

D. A dance studio recommends a membership type based on the number and type of dance classes the customer wants to attend every month.