下列关于巨幼细胞贫血的描述，错误的是

A．是一种大细胞性贫血
B．是一种小细胞低色素性贫血
C．由叶酸缺乏引起者最多见
D．由维生素B₁₂缺乏引起者多为因子缺乏所致
E．可表现为“牛肉舌”

Joe Savvy wishes to speculate in March wheat futures by selling one contract Prior to selling the one contract, Joe had no position in wheat futures at all. He sells to Billy Bland who already had a short position in the March wheat futures contract. His sale of one futures contract will produce :()

A. one contract of volume. 

B. one contract of open interest. 

C. both A and B.