Answer
$G$
Work Step by Step
If $\overline{DE} \parallel \overline{GF}$, then $\overline{DG}$ is considered a transversal. This means that $\angle D$ and $\angle G$ are same-side interior angles, and same-side interior angles are supplementary. So if we add these two angles together, then their sum would be $180^{\circ}$.
So option $G$ would be the correct answer choice.
