The year 1400 opened with more peacefulness than usual in England. Only a few months before, Richard II, weak, wicked, and treacherous, had been deposed (废黜), and Henry IV declared king in his stead. But it was only a seeming peacefulness, lasting for but a little while; for though King Henry proved himself a just and a merciful man—as justice and mercy went with the men of iron of those days—and though he did not care to shed blood needlessly, there were many noble families who had been benefited by King Richard during his reign, and who had lost somewhat of their power and prestige from the coming in of the new king.
Among these were a number of great lords who had been degraded from their former rifles and estates, from which degradation King Richard had lifted them. They planned to fail upon King Henry and his followers and to massacre (屠杀) them during a great tournament (中世纪马上比武大会) which was being held at Oxford. And they might have succeeded had not one of their own members betrayed them.
But Henry did not appear at the lists; whereupon, knowing that he had been lodging at Windsor with only a few attendants, the conspirators marched there against him. In the meantime, the king had been warned of the plot, so that instead of finding him in the royal castle, they discovered through their scouts that he had hurried to London, and that he was marching against them at the head of a considerable army. So nothing was left but flight. One and another, they were all caught and some killed. Those few who found friends faithful and bold enough to afford them shelter dragged those friends down in their own min.
Why did the nobles wish to kill Henry？

A. Henry had taken away power given to them by Richard.
B. Henry was weak, wicked, and treacherous.
C. Henry had needlessly killed members of their families.
D. Henry had killed King Richard.