The answer is 4. Usually, there might a business use-case where the service would be provided for customers who are at a different location (Europe, India) with some logic. In this case, we can use circumstancing to handle the customers by location according to the logic that would serve the purpose in those locations.
Circumstancing can be used to handle special scenarios that would normally require changes to an existing rule -the base rule- without having to change that rule. Circumstancing allows a developer to create a copy of the base rule -the circumstanced rule-, which is applied at run time when a certain condition is met.
The answer would be 3 for this as to set the goal for a case, we need to use SLA rule. SLA rule can be circumstanced and in the base rule goal will be 1 day and in the circumstanced rule with the condition, if a customer is platinum, the goal will be set to 6 hrs.
The other 3 scenarios cannot be handled by circumstancing.