If the equation of the plane containing the line $\large\frac{x-x_1}{l}=\frac{y-y_1}{m}=\frac{z-z_1}{n}$ is $a(x-x_1)+b(y-y_1)+c(z-z_1)=0$, then ?

Question

$\begin{array}{1 1} (a)\:\:ax_1+by_1+cz_1=0 & (b)\:\:al+bm+cn=0 \\ (c)\:\:\large\frac{a}{l}=\frac{b}{m}=\frac{c}{n} & (d)\:\:x_1+my_1+nz_1=0\end{array}$