Final answer:
The Spatial Join geoprocessing tool should be used in ArcGIS ModelBuilder to determine the number of points located in polygons.
Step-by-step explanation:
To determine the number of points located in polygons, the Spatial Join geoprocessing tool should be used in ArcGIS ModelBuilder. The Spatial Join tool combines attributes from one feature layer (points) to another feature layer (polygons) based on their spatial relationship. It allows you to summarize the number of points that fall within each polygon, providing a count of points per polygon.