Figure 4 shows how we worked actors into our business model in Rose — specifically, in a use-case diagram associated with customer service that's an excerpt from our business use-case model.

Please analyze all the use cases found in use case modeling, find out the related classes the relationships between them, then draw class diagram by using Rational Rose.

According to the diagram, the number of... rose sharply between... and..., before plunging back down to its original level.