This bar chart displays the average subject score for each favorite subject, with bars animating upward on load. Hovering over a bar turns it red and shows a tooltip with the exact value. Using D3 v7, the visualization fetches DSV data from a gist, parses it with `d3.dsvFormat`, aggregates values via `d3.rollup` and `d3.mean`, and renders an SVG with `scaleBand` and `scaleLinear` axes. Interactive transitions use `transition().duration()`, while mouse events update tooltip visibility and bar color.