To best show distance from a central location, a proportional symbol map would be the most effective choice. Proportional symbol maps use symbols (such as circles or other shapes) that vary in size to represent data values at specific locations, allowing for an easy visual representation of distance and magnitude from a central point.
While other options like a line cartogram or diagrammatic cartogram could also convey some spatial relationships, they are not primarily designed to show distances effectively. A choropleth map shows areas shaded or patterned in relation to a specific variable but does not adequately represent distance from a central point.