Which Statement About Queue Structure Is BEST

Which statement about queue structure is BEST?

A) Customers are more likely to feel a sense of fairness when waiting in the multiple line system than in a single line system.
B) When similarly skilled,multiple servers are available,a single line is best.
C) Customers that are in the same line must be colocated.
D) Machines needing repair are left in place and repair techs come to them;thus,the repair techs are technically the customers since they must travel to the machine.