The cardinality of a promotion's child product in Vlocity allows you to set:

A. The minimum amount of the product that can be purchased: This sets a lower limit on the quantity of the child product in the promotion, ensuring that a certain number is always included in the purchase.

B. The maximum amount of the product that can be purchased: This sets an upper limit, controlling the maximum quantity of the child product that can be included in the promotion.

D. Whether the product is optional for purchase: Cardinality can specify whether the inclusion of the child product in the promotion is mandatory or optional, providing flexibility in how promotions are structured and offered to customers.

Cardinality settings are critical for defining the purchasing rules associated with promotional bundles, allowing businesses to tailor promotions to meet specific sales strategies and customer needs.