What does DGPS stand for?

Differential GPS, known as DGPS, enhances the accuracy of standard GPS positioning by using a network of fixed ground-based reference stations. These stations continuously monitor satellite signals and calculate the difference between the positions determined by the GPS and their known fixed positions. This difference, essentially a correction factor, is then transmitted to GPS receivers to improve their position accuracy, often reducing the error from several meters to within a few centimeters. This improved precision is particularly important for applications that require high levels of accuracy, such as surveying, agriculture, and construction.

In contrast, the other terms presented do not refer to recognized systems of GPS enhancement, thus clarifying the uniqueness of Differential GPS distinctly positions it as the correct answer.