Southern gothic authors wrote about the darker side of southern society and the ways caused it to crumble.

the reconstruction era
the civil war
the economic depression
none of the above

The correct answer should be the reconstruction era

The civil war happened before the reconstruction era, and since the southern gothic writers wrote after both, it is implied that they were inspired more by the reconstruction than by the civil war itself. They mostly wrote before the economic depression that occurred around 30 years after the peak of southern gothic writing.