Look at the four Squares A,B, C and D , which indicate where the following sentence could

No other industry or consumer of wood could match the timber industry itself for the exploitation of North America's forests.

A Throughout the century, the timber industry continued to supply the single most valuable raw material for a rapidly expanding population. Between 1840 and 1860, the annual production of lumber rose from 1.6 million to 8 billion board feet.B This increase was made possible by the widespread application of steam power. Wood-fueled steam engines powered the sawmills, moved and barked the logs, and finished the boards. Railroad lines were now built right into the forests so that felled logs could be shipped directly to market.C These innovations had their greatest impact in the Great Lakes region.D By 1890 the technology of the timber industry had triumphed over the natural abundance of the forests, and woodlands that had once seemed endless were now depleted.

A．Square Ａ.

B．Square Ｂ.

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D．Square Ｄ.