Interviewer:  Can you tell me why I should hire you?
Karen:  I should be hired because I am efficient, smart, and friendly.  I am certain that I would make a great customer service manager.  I have been successful in similar positions in the past, and I am confident that I could make your company's customer service even better.
Interviewer:  That's great.  Can you tell me a little more about how you work efficiently?
Karen:  Sure.  As you know, sometimes customer service can be flooded with phone calls, complaints, or questions about a variety of topics.  It is important to answer these in a timely fashion, but it is also important to deal with the most important things first.  I am very good at organizing and assigning tasks to the customer service representatives, so the most important work gets done quickly, but we don't fall behind on the other work.
Interviewer:  That would be great if you could do that here.  We have had issues in the past when our customer service department has become overwhelmed.
Karen:  That is when I am at my best.  So, that is why I think you should hire me.