To exclude a specific subset of resources from being scheduled by the optimization engine, you use a Hard Constraint Work Rule.

Option D is correct. The Match Boolean Work Rule is designed to filter resources based on a checkbox (Boolean) field.

You would create a custom checkbox on the Service Resource object (e.g., Is_Contractor__c).

You configure the Match Boolean rule in the Scheduling Policy to enforce that Is_Contractor__c must be False.

When optimization runs, any resource where Is_Contractor__c = True fails the rule and is completely ignored/excluded from the schedule calculation.

Option A (Count Rule) limits volume, it doesn't exclude.

Options B and C (Match Field/Extended Match) match properties between the Job and the Resource (e.g., Skill or Location matching), which is not the same as a blanket exclusion of a resource type.