— Do you know Anna's telephone number?

— ______. As a matter of fact, I don't know any Anna, either. [ ]

A. I hope so

B. I think so

C. I'm afraid not

D. I'd rather not

在( )假设情形下，试图通过分析历史价格数据预测未来股价的走势，期望从过去价格数据中获益是徒劳的。

A．弱势有效市场

B．半强势有效市场

C．强势有效市场

D．半弱势有效市场