单项选择题

A certain old gentleman was very unhappy about modern education, and thought that (41) people nowadays were not being taught the (42) of knowing the difference between right and (43) .
One day he was taking a (44) in a park near his home when he saw some young boys standing (45) a small cat. The old gentleman went up to the boys and asked them (46) was happening. One of the boys said to him, "We’re having a contest. We are (47) lies, and the one who tells the biggest one gets to (48) the cat."
The old gentleman thought that this was a good chance to teach the boys a useful lesson, so he said to them, "I’ve (49) told a lie in my life." All at once there was a great shout from all the boys, and they said, "You’ve (50) ! You can take the cat!\

A.kill
B.keep
C.beat