"A teacher cannot teach his students everything they want to know however knowledgeable he is."
Which sentence means the same as the original sentence?
A、A teacher, no matter how knowledgeable he was, cannot teach his students everything they want to know.
B、A teacher, no matter how he is knowledgeable, cannot teach his students everything they want to know.
C、A teacher, no matter how knowledgeable he is, cannot teach his students everything they want to know.
D、A teacher, no matter what knowledgeable he is, cannot teach his students everything they want to know.