An organization has two lines of business: selling books for children and reselling college textbooks.

 Situational Layer Cake™ Concept: This approach allows for different rules to be applied based on varying contexts like geography, business unit, or product line, without duplicating logic that remains consistent across layers.

 Base Layer for Common UI Rules: Placing the UI rules in the base layer ensures that common interface elements are shared across all divisions, promoting reusability and consistency.

 New Layer for Division-specific Rules: Creating a new layer for the payment rules specific to each division allows customization without affecting other parts of the application. This structure enables the organization to handle division-specific requirements (like different payment methods) efficiently.

 Reference: According to Pega’s best practices for layering, it is advised to place common elements in a shared layer and division-specific elements in their respective layers. This method optimizes rule inheritance and specialization (Pega Platform 8.7 Documentation, Layering and Class Structure).