In GIS, what is the primary characteristic of nominal data?

Nominal data in GIS is primarily characterized by showing categorical distinctions. This type of data involves classifications or labels that distinguish between different groups or categories without implying any sort of quantitative value or order among them. For instance, nominal data may include classifications like land use types (e.g., residential, commercial, industrial) or soil types. Each category is unique and provides useful information for identification or grouping purposes but does not suggest any ranking or relationship between the categories.

Understanding nominal data is crucial in GIS as it allows for the organization and representation of non-numerical attributes, enabling users to analyze various thematic layers effectively. The other types of data characterized in the other choices refer to ordinal, interval, or ratio data, which involve order, numerical operations, or magnitude measurement, attributes that do not apply to nominal data.