单项选择题

The Economic Situation of Japan in the 18th Century
In the eighteenth century, Japan’s feudal overlords, from the shogun to the humblest samurai, found themselves under financial stress. In part, this stress can be attributed to the overlords’ failure to adjust to a rapidly expanding economy, but the stress was also due to factors beyond the overlords’ control. Concentration of the samurai in castletowns had acted as a stimulus to trade. Commercial efficiency, in turn, had put temptations in the way of buyers. Since most samuri had been reduced to idleness by years of peace, encouraged to engage in scholarship and martial exercises or to perform administrative tasks that took little time, it is not surprising that their tastes and habits grew expensive. Overlords’ income, despite the increase in rice production among their tenant farmers, failed to keep pace with their expenses. Although shortfalls in overlords’ income resulted almost as much from laxity among their tax collectors (the nearly invitable outcome of hereditary officeholding) as from their higher standards of living, a misfortune like a fire or flood, bringing an increase in expenses or a drop in revenue, could put a domain in debt to the city rice - brokers who handled its finances. Once in debt, neither the individual samurai nor the shogun himself found it easy to recover.
It was difficult for individual samurai overloads to increase their income because the amount of rice that farmers could be made to pay in taxes was not unlimited, and since the income of Japan’s central government consisted in part of taxes collected by the shogun from his huge domain, the government too was constrained. Therefore, the Tokugawa shoguns began to look to other sources for revenue. Cash profits from government - owned mines were already on the decline because the most easily worked deposits of silver and gold had been exhausted, although debasement of the coinage had compensated for the loss. Opening up new farmland was a possibility, but most of what was suitable had already been exploited and further reclamation was technically unfeasible. Direct taxation of the samurai themselves would be politically dangerous. This left the shoguns only commerce as a potential source of government income.
Most of the country’s wealth, or so it seemed, was finding its way into the hands of city merchants. It appeared reasonable that they should contribute part of that revenue to ease the shogun’s burden of financing the state. A means of obtaining such revenue was soon found by levying forced loans, known as goyo - kin; although these were not taxes in the strict sense, since they were irregular in timing and arbitrary in amount, they were high in yield. Unfortunately, they pushed up prices. Thus, regrettably, the Tokugawa shoguns’ search for solvency for the Government made it increasingly difficult for individual Japanese who lived on fixed stipends to make ends meet.
According to the passage, the major reason for the financial problems experienced by Japan’s feudal overload in the eighteenth century was that ______.