Which approach should be used to provide test data for a test class?

What are two ways a developer can get the status of an enquered job for a class that queueable interface? Choose 2 answers

A developer is notified that a text field is being automatically populated with invalid values.however, this should be prevented by a custom validation rule that is in placewhat could be causing this?

The following Apex method is part of the ContactService class that is called from a trigger: public static void setBusinessUnitToEMEA(Contact thisContact){ thisContact.Business_Unit__c = "EMEA" ; update thisContact; } How should the developer modify the code to ensure best practice are met?

A developer must create a ShippingCalculator class that cannot be instantiated and must include a working default implementation of a calculate method, that sub-classes can override.
What is the correct implementation of the ShippingCalculator class?