The Business Unit-level Email setting ' Subscribers will be unsubscribed from this business unit only ' is the direct, native, low-effort configuration that satisfies this exact requirement: it scopes an unsubscribe action taken within the children ' s fashion business unit to that business unit alone, leaving the subscriber ' s opt-in status intact across all other business units, including the parent Enterprise business unit — with no custom development, attribute engineering, or filter-building required, which aligns with the customer ' s minimal technical resources. This is a single checkbox-level setting change, making it by far the lowest-effort, most maintainable solution among the options. ' Use separate Subscription Center for this business unit ' (A) affects which subscription-preference page a subscriber sees when managing their preferences, not whether an unsubscribe event is scoped to one business unit versus propagating account-wide — it solves a different problem. Option B describes manually engineering a custom filter against the All Subscribers list to track unsubscribes, and option D proposes custom attribute-based tracking — both are unnecessarily complex, developer-dependent workarounds for a requirement natively solved by a single setting. Reference: Business Unit Email Settings, Unsubscribe Scope Configuration.