单项选择题

The business cycle is composed of many phases and one of them is the expansion phase. This phase is a two-fold one, including recovery and prosperity.
During the recovery period there is an ever-growing expansion of existing equipment. And new facilities for production are created. More businesses are created and older ones expanded. Improvements of serious kinds are made. There is an ever increasingly positive view about the future of economic growth. Much capital is invested in machinery or "heavy" industry. More labor is employed. More raw materials are required.
As more parts of the economy develop, other parts are affected. For example, the expansion in automobiles results in an expansion of the steel and rubber industries. Roads are required; thus the cement and machinery industries are activated. Demand for labor and materials results in greater prosperity for workers and suppliers of raw materials. This increases the amount of goods bought and sold. Thus prosperity develops among the various parts of the population.
This prosperity, period may continue to rise without an obvious end. However, a time comes when this phase reaches a peak and stops going upwards. This is the end of the expansion phase.
Which is probably the best title for this passage

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