“跳一跳，摘桃子”是讲教学目标的设计要 【】

A．内容具有科学性和思想性

B．便于检测

C．系统完整

D．难度适中

Mark Williamson is "bearish" on ABC Manufacturing Company. Williamson is so convinced that ABC is overpriced, two weeks ago, he shorted 100000 shares. Today, Williamson is "surfing" several popular investment bulletin boards on the internet and posting false derogatory comments about company management. According to Standard Ⅱ (B), Market Manipulation, Williamson has engaged in:（）

A. transaction-based manipulation, but not information-based manipulation. 

B. both transaction-based manipulation and information-based manipulation. 

C. information-based manipulation, but not transaction-based manipulation.