Text D 　　The bubonic plague, also known as the Black Death, swept through Europe between 1347and 1451, and remained endemic in England until 1666. Carried by the fleas which lived onthe black rat, the plague reached Western Europe from the Crimea, possibly on Genoesemerchant ships, and spread north from the Mediterranean during 1348. Everywhere the deathrate was high and, worse still, the plague recurred regularly. The English population fell fromnearly four million in 1348 to just over two million in 1400. 　　Every feature of decline in the late Middle Ages, from deserted villages to a slump inmonastic vocation has since been attributed to the Black Death. But this decline was, in fact,more the consequence of growing malnutrition, which became more and more widespread asthe uncontrolled population growth of the 13th century pushed thousands of cultivators intomarginal lands. 　　The Black Death was the crisis. It grimly restored the balance between menand their food supply；and, short of an agrarian revolution, there was nothing else that could.The Black Death was ultimately the catalyst in another process – the commutation oflabor service. The movement to change the labor system from a feudal one （wherein laborerswere required to work in return for goods and protection） to a monetary one was already inprogress. However, landowners obviously opposed the monetary system, because they had topay for labor. But the attempts by employers to withhold wages and to restore labor serviceeverywhere were bound to fail, since the situation now favored the employees. Ultimately, theemployers had to give away, and the commutation movement rapidly accelerated.
31. How did the Black Death affect the commutation of labor service in the long run？
(A) It became faster than before.
(B) It continued, but only for a short time.
(C) It stopped it temporarily.
(D) It increased, but at a slower rate.