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The increase in rewards still did not attract young people to this hard life, and convicted criminals and slaves were pressed into service.
In the late thirteenth century, northern Italian cities such as Genoa, Florence, and Venice began an economic resurgence that made them into the most important economic centers of Europe. By the seventeenth century, however, other European powers had taken over, as the Italian cities lost much of their economic might.
This decline can be seen clearly in the changes that affected Venetian shipping and trade. First, Venice's intermediary functions in the Adriatic Sea, where it had dominated the business of shipping for other parties, were lost to direct trading. In the fifteenth century there was little problem recruiting sailors to row the galleys (large ships propelled by oars): guilds (business associations) were required to provide rowers, and through a draft system free citizens served compulsorily when called for. In the early sixteenth century the shortage of rowers was not serious because the demand for galleys was limited by a move to round ships (round-hulled ships with more cargo space), which required fewer rowers. But the shortage of crews proved to be a greater and greater problem, despite continuous appeal to Venice's tradition of maritime greatness. Even though sailors' wages doubled among the northern Italian cities from 1550 to 1590, this did not elicit an increased supply.
The problem in shipping extended to the Arsenale, Venice's huge and powerful shipyard. Timber ran short, and it was necessary to procure it from farther and farther away. In ancient Roman times, the Italian peninsula had great forests of fir preferred for warships, but scarcity was apparent as early as the early fourteenth century. Arsenale officers first brought timber from the foothills of the Alps, then from north toward Trieste, and finally from across the Adriatic. Private shipbuilders were required to buy their oak abroad. As the costs of shipbuilding rose, Venice clung to its outdated standards while the Dutch were innovating in lighter and more easily handled ships.
The step from buying foreign timber to buying foreign ships was regarded as a short one, especially when complaints were heard in the latter sixteenth century that the standards and traditions of the Arsenale were running down. Work was stretched out and done poorly. Older workers had been allowed to stop work a half hour before the regular time, and in 1601 younger workers left with them. Merchants complained that the privileges reserved for Venetian-built and -owned ships were first extended to those Venetians who bought ships from abroad and then to foreign-built and -owned vessels. Historian Frederic Lane observes that after the loss of ships in battle in the late sixteenth century, the shipbuilding industry no longer had the capacity to recover that it had displayed at the start of the century.
The conventional explanation for the loss of Venetian dominance in trade is the establishment of the Portuguese direct sea route to the East, replacing the overland Silk Road from the Black Sea and the highly profitable Indian Ocean-caravan-eastern Mediterranean route to Venice. The Portuguese Vasco da Gama's voyage around southern Africa to India took place at the end of the fifteenth century, and by 1502 the trans-Arabian caravan route had been cut off by political unrest.
The Venetian Council finally allowed round ships to enter the trade that was previously reserved for merchant galleys, thus reducing transport costs by one third. Prices of spices delivered by ship from the eastern Mediterranean came to equal those of spices transported by Portuguese vessels, but the increase in quantity with both routes in operation drove the price far down. Gradually, Venice's role as a storage and distribution center for spices and silk, dyes, cotton, and gold decayed, and by the early seventeenth century Venice had lost its monopoly in markets such as France and southern Germany. Venetian shipping had started to decline from about 1530-before the entry into the Mediterranean of large volumes of Dutch and British shipping-and was clearly outclassed by the end of the century. A contemporary of Shakespeare (1564–1616) observed that the productivity of Italian shipping had declined, compared with that of the British, because of conservatism and loss of expertise. Moreover, Italian sailors were deserting and emigrating, and captains, no longer recruited from the ranks of nobles, were weak on navigation.
题干分析：待插入句“The increase in rewards still did not attract young people to this hard life, ... ”这里the increase可能指代的是前文提到过的内容，并且这里的still也表明在前文已经说了不能吸引人去从事这个工作，符合这两个特点的只有D选项。
首先段落中找回报增加/收入增长，定位到了最后一句，再判断选C还是D。注意到D前的句子说wages doubled和D中的increase in reward呼应，D前的did not elicit an increased supply和D中的did not attract young people呼应，所以应该选D。