Final answer:
A URL referencing a feature layer is the correct parameter to use when creating a FeatureLayerCollection. This URL allows access to GIS data on the server, enabling the creation of the collection.
Step-by-step explanation:
When creating a FeatureLayerCollection, the correct type of parameter to use is b) A URL referencing a feature layer. This URL is essentially the address where the feature layer can be accessed on a GIS (Geographic Information System) server. In the context of ArcGIS, for example, a FeatureLayerCollection can be created by passing this URL to connect to a specific feature service hosted on the server, allowing one to essentially tap into a set of features stored as GIS data.