An after trigger on the Account object performs a DML update operation on all of the child Opportunities of an Account. There are no active triggers on the Opportunity object, yet a "maximum trigger depth exceeded" error occurs in certain situations.
Which two reasons possibly explain the Account trigger firing recursively? (Choose two.)

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?

Which control statement should a developer use to ensure that a loop body executes at least once?

Which two number expressions evaluate correctly? (Choose two.)

Which three resources in a Lightning Component Bundle can contain JavaScript functions? Choose 3