The best choice for capturing geographic location data, such as crossroads or location markers provided by customers, is the Geolocation field type. This field type stores latitude and longitude data, allowing accurate pinpointing of locations on a map. Geolocation fields are suitable for any application that needs to handle coordinates for mapping and proximity calculations.
A: Number field is not specific enough for geographical coordinates.
C: Reference fields link to other records, not geographical data.
D: External Lookup is used to link to external objects, not for storing coordinates.
Reference: Geolocation Custom Fields on Salesforce Help