What is the key component of a Next-Best-Action strategy?

The key component of a Next-Best-Action strategy is a strategy, which is a graphical representation of the business logic that determines which actions to offer to each customer and in what order. A strategy can use various components, such as business rules, predictive models, filters, prioritizers, etc., to achieve this goal. References: https://academy.pega.com/module/one-one-customer-engagement/topic/next-best-action-designer