单项选择题

One phase of the business cycle is the expansion phase. This phase is a twofold one,including recovery and prosperity. During Line the recovery period there is ever-growing expansion of existing facilities, and new facil-ities for production are created. More busi-nesses are created and older ones expanded.Improvements of various kinds are made.There is an ever-increasing optimism about the future of economic growth. Much capi-tal is invested in machinery or "heavy" indus-try. More labor is employed. More materials are required. As one part of the economy develops, other parts are affected. For exam- ple, a great expansion in automobiles results in an expansion of the steel, glass, and rubber industries. Roads are required; thus the cement and machinery industries are stimu-lated. Demand for labor and materials results in greater prosperity for workers and suppliers of raw materials, including farmers. This increases purchasing power and the volume of goods bought and sold. Thus, prosperity is diffused among the various segments of the population. This prosperity period may con-tinue to rise and rise without an apparent end.However, a time comes when this phase reaches a peak and stops spiraling upwards.This is the end of the expansion phase.

Which of the following statements best exemplifies the optimism mentioned in the boldfaced sentence of the passage as being part of the expansion phase？（）

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