This scenario requires managing availability for resources who work across multiple territories (Primary and Secondary memberships) specifically for "off-hours" emergencies.

Option D is correctbecause Shifts in Salesforce Field Service allow you to define ad-hoc availability outside of standard Operating Hours. Crucially, if you create a Shiftwithout specifying a Service Territory, that availability applies to the resource'sPrimary Territoryby default. However, because the resource also holdsSecondary Territory Membershipsfor the other business units, the scheduling engine (specifically the "Match Territory" Work Rule) recognizes this availability as valid for those territories as well, provided the shift falls within the membership dates.

Setting the Time Slot Type to'Designated'(or 'Extended') is the standard way to mark time for specific work types (like Emergencies) using Work Rules that filter on those time slot types.

Option B is incorrect because creating a separate shift foreveryterritory is administrative overhead and unnecessary when a single non-territory-specific shift can cover the resource's availability across their memberships.

Option A is factually incorrect; resources can have multiple territory memberships.