#### Answer

$\angle C$

#### Work Step by Step

In congruent polygons, vertices are named in the exact order of their matching angles and sides.
If $ABCD$ is congruent to $EFGH$, then vertex $A$ corresponds to vertex $E$, vertex $B$ corresponds to vertex $F$, vertex $C$ corresponds to vertex $G$, and vertex $D$ corresponds to vertex $H$.
Therefore, $\angle G$ is congruent to $\angle C$.