【单选题】

Between the invention of agriculture and the commercial revolution that marked the end of the MiddleAges, wealth and technology developed slowly indeeD、Medieval historians tell of the centuries it took for key inventions like the watermill or the heavy plow to diffuse across the landscape.During this period, increases in technology led to increases in the population, with little if any appearing as an improvement in the median standard of living.

Even the first century of the industrial revolution produced more "improvements" than "revolutions" in standards of living. With the railroad and the spinning and weaving of textiles as important exceptions, most innovations of that period were innovations in how goods were produced and transported, and in new kinds of capital, but not in consumer goods. Standards of living improved but styles of life remained much the same.
The eighteenth and nineteenth centuries saw a faster and different kind of change. For the first time, technological capability outran population growth and natural resource scarcity.By the last quarter of the nineteenth century, the typical inhabitant of the leading economies—aBritish, aBelgian, anAmerican, or anAustralian had perhaps three times the standard of living of someone in a pre-industrial economy.
Still, so slow was the pace of change that people, or at least aristocratic intellectuals, could think of their predecessors of some two thousand years before as effectively their contemporaries. Marcus TulliusCicero, a Roman aristocrat and politician, might have felt more or less at home in the company of Thomas Jefferson. The plows were better in Jefferson’s time. Sailing ships were much improveD、However, these might have been insufficient to create a sense of a qualitative change in the order of life for the elite. Moreover, being a slave of Jefferson was probably a lot like being a slave ofCicero.
So slow was the pace of change that intellectuals in the early nineteenth century debated whether the industrial revolution was worthwhile, whether it was an improvement or a degeneration in the standard of living. Opinions were genuinely divided, with as optimistic a liberal as John Stuart Mill coming down on the "pessimist" side as late as the end of the 1840s.
In the twentieth century, however, standards of living explodeD、In the twentieth century, the magnitude of the growth in material wealth has been so great as to make it nearly impossible to measure.Consider a sample of consumer goods available through Montgomery Ward in 1895 when a one-speed bicycle cost $65. Since then, the price of a bicycle measured in "nominal" dollars has more than doubled (as a result of inflation). Today, the bicycle is much less expensive in terms of the measure that truly counts, its "real" price: the work and sweat needed to earn its east. In 1895, it took perhaps 260 hours’ worth of the averageAmerican worker’s production to amass enough money to buy a one-speed bicycle. Today an averageAmerican worker can buy one—and of higher quality—for less than 8 hours worth of production.
On the bicycle standard (measuring wealth by counting up how many bicycles the labor can buy) the averageAmerican worker today is 36 times richer than his or her counterpart was in 1895. Other commodities would tell a different story.An office chair has become 12.5 times cheaper in terms of the time it takes the average worker to produce enough to pay for it.
A、Steinway piano or an accordion is only twice as cheap.
A、silver teaspoon is 25 percent more expensive.
Thus the answer to the question "How much wealthier are we today than our counterparts of a century ago " depends on which commodities you view as important. For many personal services—having a butler to answer the door and polish your silver spoons—you would find little difference in average wealth between 1895 and 1990: an hour of a butler’s time costs about the same then as no