What is the general datum plane referred to by surveyors throughout South Dakota?

The North American Datum is the correct choice because it serves as a framework for geospatial measurements across various applications, including land surveying, mapping, and civil engineering in the United States, including South Dakota. This datum provides a consistent geographical reference for locating features on the earth's surface and is fundamental in establishing property boundaries and conducting accurate surveys.

The North American Datum 1983 (NAD83) specifically allows surveyors to accurately measure and represent positions on the Earth's surface, making it essential for real estate and land development. The other options represent different geographic or geodetic reference systems that do not serve the same purpose in the context of surveying in South Dakota. For instance, the South American Datum would apply to areas in South America, while the International Datum and Geographic Coordinate System are broader frameworks not limited to North American contexts. Thus, the North American Datum is the one most relevant and utilized by surveyors in South Dakota.