问题如下：
Which of the following statements most likely contributes to the view that derivatives have some role in causing financial crashes?
选项：
A.A Derivatives are the primary means by which leverage and related excessive risk is brought into financial markets.
B.Growth in the number of investors willing to speculate in derivatives markets leads to excessive speculative trading.
C.Restrictions on derivatives, such as enhanced collateral requirements and credit mitigation measures, in the years leading up to crashes introduce market rigidity.
解释：
B is correct. Opponents of derivatives claim that excessive speculative trading brings instability to the markets. Defaults by speculators can lead to defaults by their creditors, their creditors’ creditors, and so on. A is incorrect because derivatives are one of many mechanisms through which excessive risk can be taken. There are many ways to take on leverage that look far less harmful but can be just as risky. C is incorrect because responses to crashes and crises typically call for more rules and regulations restricting the use of derivatives, such as requiring more collateral and credit mitigation measures. Such rules and regulations are generally implemented after a crash and are directed at limiting government bailouts of the costs from derivatives risks.
老师 A为什么不对？衍生品的杠杆会引起金融危机，不对吗？
