【题目】Finding in-formation in today's world is easy. The _____ is how you can tell if the in-formation you get is useful or not.
A. ability
B. competition
C. challenge
D. knowledge
在线课程【答案】C
【解析】ability能力，才干；com-petition 竞争，竞赛；challenge挑战； knowledge知识，学问。