As a law graduate, he ought to know that eyewitness______ is notoriously unreliable, espec

As a law graduate, he ought to know that eyewitness______ is notoriously unreliable, especially so when the witness is not an expert.

A．insight

B．remark

C．argument

D．testimony

请帮忙给出正确答案和分析，谢谢！