This example shows a horizontal bar chart of the top 20 countries by COVID-19 cases, using data loaded from a CSV file via `d3.csv` and rendered with React and D3 v5. The visualization uses `scaleBand` for the y-axis, `scaleLinear` for the x-axis, and draws SVG `<rect>` elements for the bars with tick marks and labels generated from `xScale.ticks()`. The chart updates reactively from React state, with the data slice and parsing handled inside a `useEffect` hook.