A mosaic dataset is the optimal storage mechanism for this scenario. It is a data model within an enterprise geodatabase specifically designed to manage, view, and query large collections of raster and image data. It stores metadata and references to the source imagery (which can remain in a centralized folder) rather than the pixels themselves. This allows for dynamic mosaicking, on-the-fly processing, and efficient serving of imagery as a single layer across an organization, which directly meets the administrator's requirements for enterprise-wide access.

A. Raster dataset: A raster dataset typically represents a single raster image. It is not designed to manage or visualize a collection of multiple images as a single, cohesive layer.

B. Raster catalog: A raster catalog is a legacy data model for managing collections of rasters. While functional, it has been largely superseded by the mosaic dataset, which offers superior performance and more advanced capabilities.

1. Esri ArcGIS Pro Documentation, "What is a mosaic dataset?": "A mosaic dataset is a data model in the geodatabase that is used to manage a collection of raster datasets (images) stored as a catalog and viewed as a single mosaicked image." This source confirms its purpose for managing collections.

2. Esri ArcGIS Pro Documentation, "Fundamentals of raster storage": In the section comparing storage options, it states, "Mosaic datasets are ideal for managing and visualizing large collections of imagery... They are also the best way to serve imagery." This highlights its suitability for enterprise access.

3. Esri ArcGIS Pro Documentation, "Raster catalog properties": "Raster catalogs are useful for displaying adjacent, non-overlapping raster datasets... If you have overlapping raster datasets, it is recommended that you use a mosaic dataset." This indicates the mosaic dataset is the more modern and recommended approach.