There is no doubt,  in my opinion,  ________matters is not the speed,  but the quality of the products.[ ]

A. that  

B. which

C. what that  

D. that what

蜜炙中药饮片，其杂质含量不得超过

A．0.5%

B．1%

C．1.5%

D．2%

E．3%