If $r_1$ and $r_2$ are regression coefficients of $y$ on $x$ and $x$ on $y$ respectively

Question

$\begin {array} {1 1} (A)\;r_1+r_2=2r & \quad (B)\;r_1+r_2<2r \\ (C)\;r_1+r_2 \geq 2r & \quad (D)\;None \: of \: these \end {array}$