Final answer:
The map of Louisiana's sixty-four parishes discussed in the question is a subject of 3. Geography. It involves understanding the division of land into political units and analyzing cultural and linguistic distributions within the state.
Step-by-step explanation:
The subject of the map of Louisiana showing the sixty-four governmental divisions called parishes pertains to 3. Geography, as it deals with the division of land into political units and the representation of cultural practices and languages within a geographic area.
When looking at a map that outlines the parishes in Louisiana, you are exploring how the land is divided for governmental purposes, which is a geographical concept involving man-made borders. The references to the cadastral patterns along the Mississippi River, the various cultural regions, language distributions, and historical pieces like the Land Ordinance of 1787 further emphasize the map's geographical nature.
In addition, considering concepts like folk regions and linguistic distributions, as mentioned in the provided descriptions, helps illustrate how geography influences social and cultural systems. These concepts require a geographic understanding that goes beyond simply locating areas on a map; they necessitate an analysis of how physical and human factors interact to shape regions.