Which ArcGIS Desktop extension should be enabled to use the Block Statistics geoprocessing tool when calculating the mean slope per watershed?

The Block Statistics geoprocessing tool is part of the Spatial Analyst extension in ArcGIS Desktop. This tool is specifically designed for analyzing raster data and performing statistical calculations over blocks of raster cells, such as calculating the mean slope per watershed. When using the Block Statistics tool, you can aggregate and summarize raster values within specified zones or blocks, making it particularly useful for spatial analysis involving continuous data like slope.

In contrast, the other extensions mentioned serve different purposes:

• Geostatistical Analyst focuses on advanced geostatistical modeling and interpolation, which is not directly related to the use of Block Statistics.

• Network Analyst is geared towards analyzing networks, like transportation or utility systems, and does not pertain to block-based statistical calculations.

• Schematics is used for creating and visualizing schematic drawings, often related to network diagrams, which also does not apply to raster analysis.

Given the specific function of the Block Statistics tool in relation to raster data analysis, enabling the Spatial Analyst extension is requisite for accessing and utilizing this tool effectively.