单项选择题

Reduce 50 g to No.180 powder and detrmine the loss on drying by drying 2g to constant weight at 100℃ to 105℃在上述药品的干燥失重实验中,将多少克的待测样品干燥至恒重()

A.50g
B.180g
C.2g
D.100g
E.105g