问题如下：
1. Which of the following is not a key assumption of APT, which is used by Altuve to evaluate strategies and manage risks?
选项：
A. A factor model describes asset returns.
B. Asset-specific risk can be eliminated through diversification.
C. Arbitrage opportunities exist among well-diversified portfolios.
解释：
C is correct.
Arbitrage pricing theory (APT) is a framework that explains the expected return of a portfolio in equilibrium as a linear function of the risk of the portfolio with respect to a set of factors capturing systematic risk. A key assumption of APT is that, in equilibrium, there are no arbitrage opportunities.
考点：APT模型
解析：APT模型共有3个假设
1. A factor model describes asset returns.
2. There are many assets, so investors can form well-diversified portfolios that eliminate asset-specific risk
3. No arbitrage opportunities exist among well-diversified portfolios
C选项错，对应第三个假设，充分分散的组合中是没有套利机会的。
如果asset firm specific risk是可以充分分散掉，那为什么还有给予补偿呢？ 我的理解是在均衡模型下才说asset specific risk是可以被分散掉，所以不用给予补偿， 但是在回归模型下，（APT）下，asset specific risk是用来解释风险溢价来源的， 麻烦老师解释一下选项B，以及看一下我的理解哪里有问题
