--Maths isn't as -as Chinese.--I agree with you.I think Chin

--Maths isn't as _as Chinese.--I agree with you.I think Chinese is _ than any other subject.
A.easy; easier B.easier; easier C.easy;harder D.hard; easier
为什么答案选C,不选D?
D选项的easier同样是比较级。正确答案确实写错了，书上的参考答案是A 选项。