一道不懂的英语选择题Since he spent his chidhood in France,Jack is able

一道不懂的英语选择题
Since he spent his chidhood in France,Jack is able to converse in French_____.
A rather good B quite better C fairly more D rather well
我看到好多人多说选A,但是不管怎么说good都是形容词,查不出good可以做副词的用法 很明显这里应该用副词 那么为什么不选D呢 莫非rather good中good有特殊用法?
better确实没错 但是quite能够修饰比较级吗？貌似只有much little bit far等几个才可以的 应该只有可能选A或者D的~