Which of the following formats are USGS Topo maps available in?

USGS Topo maps are available in multiple formats, but GeoTIFF is particularly significant for GIS applications due to its geospatial capabilities. GeoTIFF is a raster graphics format that includes georeferencing information, allowing the map to be accurately overlaid on other geographic data and utilized in various GIS software. This makes GeoTIFF an ideal format for researchers, planners, and others who rely on spatial analysis and need to incorporate topographical information into their work.

In contrast, while PDF and KML formats are useful in specific contexts—PDF being more suited for viewing and printing documents containing static information, and KML being utilized for representing geographic data within applications like Google Earth—they do not combine high-resolution imagery with georeferencing in the same way that GeoTIFF does. DOCX, as a word processing format, is not applicable for the representation of map data. Thus, GeoTIFF stands out as the most appropriate choice for working with USGS Topo maps in a GIS environment.