英国药典(93年版)规定大黄含羟基葸醌类衍生物，以大黄酸计不得少于2．5%，其英语表示法是

A．Itcontainsnolessthan2．5%ofhydroxyanthracenederivatives,calculatedasrhein．
B．Itcontainsdownto2．5%ofhydroxyanthracenederivatives,calculatedasrhein．
C．Itcontainsmorethan2．5%ofhydroxyanthracenederivatives,calculatedasrhein．
D．Itcontainsupto2．5%ofhydroxyanthracenederivatives,calculatedasrhein．
E．Itcontainsnotlessthan2．5%ofhydroxyanthracenederivatives,calculatedasrhein．