问题如下：
Which of the following statements is correct?
选项：
A. The security characteristic line's slope is an asset's beta.
B. The security characteristic line's slope is an asset's excess return.
C. The security characteristic line's slope is an asset's risk premium.
解释：
A is correct.
The security characteristic line is a plot of the excess return of the security on the excess return of the market. The slope of SCL is the asset's beta.
请问sml的slope为什么不是market risk premium， 记得老师在课上提到market risk premium对于全部asset都是一样的， 而不一样的是每一个资产对应市场的beta。 然而在这直线上每一点算出来的斜度不都一样，所以不应该是risk premium吗