一道英语选择题...关于动词介词搭配的

一道英语选择题...关于动词介词搭配的
Instead, I'll _____ on the differences between the two versions; unfortunately most of the differences took away from the original films, _____ I think is truly excellent.
A、comment; which
B、analyze; as
请问为什么选B而不选A呢?话说,其实我整道题的句义都没看懂.