通过进行骨髓检查能做出准确判断的是（）

A.急性再生障碍性贫血

B.免疫性贫血

C.失血性贫血

D.地中海性贫血

E.继发性贫血

Assume a firm with a debt to equity ratio of 0.50 and debt equal to $ 35 million makes a commitment to acquire raw materials with a present value of $12 million over the next 3 years. For purposes of analysis the best estimate of the debt to equity ratio should be :（）

A. 0.343.

B. 0.500.

C. 0.671.