Which of the following is the correct calculation for the required rate of return under the CAPM?

$($a$)$ beta $($market risk premium$)$

$($b$)$ beta $+$ market risk premium

$($c$)$ risk$-$free rate $+$ risk premium

$($d$)$ risk$-$free rate $($market risk premium$)$

$($e$)$ None of the above