Since all picklist values for the Status field on Tasks are configurable I don't think I can simply set the Status to "Completed" as that picklist value could have been deleted/renamed.
I tried getting the picklist values for the Status field, but when I list the picklist values with the REST API or via Apex, I don't seem to get this information. All I get is Label, Value, isActive, and isDefaultValue. Is there any way to know if one of the picklist values is considered closed? or to reliably set a Task to "closed" without knowing that?