Final answer:
The category of the GIS application that tracks changes in ridership on mass transit systems is Urban planning. GIS can be used to analyze spatial data layers to determine the best location for a retail store and track patterns in ridership on mass transit systems.
Step-by-step explanation:
The category of the Geographic Information System (GIS) application that tracks changes in ridership on mass transit systems is Urban planning. GIS can be used to analyze spatial data layers such as population distribution, street arrangements, and the locations of similar stores to determine the best location for a retail store. Similarly, GIS can track patterns in ridership on mass transit systems to help planners make informed decisions.