My tired brain is berating my inner self for waiting till the end of the day to look at the QOD. But I'm glad I did.

I was able to choose the correct answer by looking for whether the outer (left or right) joins would allow "extra" rows to be selected. Since the original query was dependent (via the inner join) on the presence of Ordersfor the Customers to be available for possible use in the left outer join to Employees, I looked for which choice supported that relationship. #4 has it right up front with the inner join from Orders to Customers, so it was a short hop from that recognition to picking it as the answer.

I'm just glad at this point that it was a multiple-choice question.