An alternating current generator has an internal resistance $R_g$ and an internal reluctance $X_g$.It is used to supply power to a passive loud consisting of a resistance $R_g$ and a reluctance $x_L$ . For maximum power to be delivered from the generator to the load, the value of $X_L$ is equal to

Question

$\begin{array}{1 1} 0 \\ X_g \\ -X_g \\ R_g \end{array}$