prep 中一题 对答案有疑问！

  If 500 is the multiple of 100 that is closest to X and 400 is the multiple of 100 that is closest to Y, which multiple of 100 is closest to X+Y?(1)X<500(2)Y<400

 gmat prep中答案为：C

 看了以前的帖子 说应该为 E

 我觉得也应该是E 可是软件是OFFICIAL的 应该不会错...

 一定要在确定一下 谢谢！

E吧