This example visualizes the global cumulative COVID-19 death toll over time, with a horizontal marker line at the 10,000-death threshold. The line chart uses React and D3 v5, employing `d3.scaleTime`, `d3.scaleLinear`, and `d3.line` to render the SVG path. Data is fetched as CSV from the CSSEGISandData COVID-19 repository and transformed with `d3.csv` and `d3.timeParse`. The marker line is drawn as an SVG `<line>` element at the y-axis position corresponding to 10,000 deaths, highlighting the pandemic's early growth milestone.