This chart plots the cumulative total of coronavirus deaths over time, with a horizontal marker line highlighting the moment deaths crossed 10,000. The React component uses D3 scales (`scaleTime`, `scaleLinear`) and a `line` generator to render an SVG path. Vertical and horizontal marker lines, with labels, are built as React subcomponents. Data comes from the Johns Hopkins COVID-19 time-series CSV, which is loaded and transformed with `csv` and `timeParse`.