Select all that apply

The nonzero slope coefficient test is used for a renowned financial application referred to as the capital asset pricing model $($CAPM$).$The model $y=ax,$ is essentially a simple linear regression model that uses a and $,$ in place of the usual ${}_0$ and ${}_1,$ to represent the intercept and the slope coefficients, respectively. Which of the following is true about the slope coefficient $,$ called the stock's beta? Select all that apply.

When $$ equals $0,$ any change in the market return leads to an identical change in the given stock return.

When $$ equals $1,$ any change in the market return leads to an identical change in the given stock return.

A stock for which $>1$ is considered more "aggressive" or riskier than the market

Measures how sensitive the stock's return is to changes in the level of the overall market