老师您好，可否详细介绍下up and out、down and out期权是什么以及特点？谢谢！

NO.PZ2020033001000041 问题如下 Whiof the following statements best illustrates the main limitations of the BSM option pricing mol? A.For up-anout calls anputs, when the knock-out strike priis equto the strike prianthe interest rate is equto the return on the unrlying asset, the BSM mol is insensitive to changes in implievolatility. B.The volatility smile incates ththe implievolatility of in-the-money call anput options is relatively low. C.For wn-anout calls anputs, when the knock-out strike priis smaller ththe strike prianthe interest rate is higher ththe return on the unrlying asset, the BSM mol is not sensitive to changes in option maturity. The BSM mol assumes thvolatility changes the market changes A is correct.考点BSM模型的缺点解析作为结论了解即可因为BSM假设的是constant volatility，但是实际中，在knoout价等于行权价，以及unrlying收益率等于利率时，期权价格对隐含波动率会很敏感。因此BSM的假设隐含波动率变化不敏感就是模型的缺陷。 如题

NO.PZ2020033001000041 问题如下 Whiof the following statements best illustrates the main limitations of the BSM option pricing mol? A.For up-anout calls anputs, when the knock-out strike priis equto the strike prianthe interest rate is equto the return on the unrlying asset, the BSM mol is insensitive to changes in implievolatility. B.The volatility smile incates ththe implievolatility of in-the-money call anput options is relatively low. C.For wn-anout calls anputs, when the knock-out strike priis smaller ththe strike prianthe interest rate is higher ththe return on the unrlying asset, the BSM mol is not sensitive to changes in option maturity. The BSM mol assumes thvolatility changes the market changes A is correct.考点BSM模型的缺点解析作为结论了解即可因为BSM假设的是constant volatility，但是实际中，在knoout价等于行权价，以及unrlying收益率等于利率时，期权价格对隐含波动率会很敏感。因此BSM的假设隐含波动率变化不敏感就是模型的缺陷。 A,insentive to change in implievolitility, BSM是假设volatility相同吧？所以A为啥对c,一个option maturity，不懂B，为啥错是因为volitility应该不变吧

NO.PZ2020033001000041 问题如下 Whiof the following statements best illustrates the main limitations of the BSM option pricing mol? A.For up-anout calls anputs, when the knock-out strike priis equto the strike prianthe interest rate is equto the return on the unrlying asset, the BSM mol is insensitive to changes in implievolatility. B.The volatility smile incates ththe implievolatility of in-the-money call anput options is relatively low. C.For wn-anout calls anputs, when the knock-out strike priis smaller ththe strike prianthe interest rate is higher ththe return on the unrlying asset, the BSM mol is not sensitive to changes in option maturity. The BSM mol assumes thvolatility changes the market changes A is correct.考点BSM模型的缺点解析作为结论了解即可因为BSM假设的是constant volatility，但是实际中，在knoout价等于行权价，以及unrlying收益率等于利率时，期权价格对隐含波动率会很敏感。因此BSM的假设隐含波动率变化不敏感就是模型的缺陷。 老师对于CFor wn-anout calls anputs, when the knock-out strike priis smaller ththe strike prianthe interest rate is higher ththe return on the unrlying asset, the BSM mol is not sensitive to changes in option maturity.哪里可以看成knoout strikeknoout strike低于普通的行权价的时候，此时期权依然是正常存续的

NO.PZ2020033001000041 问题如下 Whiof the following statements best illustrates the main limitations of the BSM option pricing mol? A.For up-anout calls anputs, when the knock-out strike priis equto the strike prianthe interest rate is equto the return on the unrlying asset, the BSM mol is insensitive to changes in implievolatility. B.The volatility smile incates ththe implievolatility of in-the-money call anput options is relatively low. C.For wn-anout calls anputs, when the knock-out strike priis smaller ththe strike prianthe interest rate is higher ththe return on the unrlying asset, the BSM mol is not sensitive to changes in option maturity. The BSM mol assumes thvolatility changes the market changes A is correct.考点BSM模型的缺点解析作为结论了解即可因为BSM假设的是constant volatility，但是实际中，在knoout价等于行权价，以及unrlying收益率等于利率时，期权价格对隐含波动率会很敏感。因此BSM的假设隐含波动率变化不敏感就是模型的缺陷。 这道题在讲义讲到这部分的时候出出来，合适吗？我怎么在讲义里没看到这道题涉及到的知识点？