In the Capital Asset Pricing Model (CAPM),beta Measures

In the Capital Asset Pricing Model (CAPM) ,beta measures

A) the standard deviation of a single asset.
B) the price volatility of a single security not held in a portfolio.
C) the degree of correlation between two securities.
D) the historical relationship between the returns from an asset and the returns from the efficient portfolio.
E) the firm-specific risk of an asset.