The discussion of the regional bank (line 13-24) serves which of the following functions within the passage as a whole？

A. It describes an exceptional case in which investment in service actually failed to produce a competitive advantage.
B. It illustrates the pitfalls of choosing to invest in service at a time when investment is needed more urgently in another area.
C. It demonstrates the kind of analysis that managers apply when they choose one kind of service investment over another
D. It supports the argument that investments in certain aspects of service are more advantageous than investments in other aspects of service.
E. It provides an example of the point about investment in service made in the first paragraph.