This example presents a parallel coordinates chart showing the relationship between college tier and five numerical factors: the proportion of female students, married students, parental income, kid earnings, and mobility rate. The visualization uses grey background lines for all data categories and blue foreground lines for the currently focused tier. Users can brush along any axis to filter the displayed lines. The implementation relies on d3.v3, specifically using `d3.svg.brush` for interactive filtering, `d3.scale.ordinal().rangePoints` for the categorical axis, and `d3.svg.line()` to draw the polylines, with data loaded from the included `mrc_table.csv` file.