Which formulas provide the CAPM expected return$-$beta relationship? $($Recall that $E(r_i)$ is the expected return of security $i,$ and $E(R)$ is its expected excess return.$)$

$E(r_i)=r_f+{}_i[E(r_M)-r_f]$

$E(r_i)=i[E(r_M)-r_f]$

$E(R_i)={}_{i}E(R_M)$

$E(R_i)=ai+iE(R_M)$