This vertical bar chart visualizes the ten most populous countries, using data from the United Nations World Population Prospects 2019. The visualization renders as an SVG via React, with bars drawn by the custom `Marks` component. Categorical country names are placed on the x-axis via `xScale`, while the `yScale` maps population values to bar heights. The chart uses `d3.scaleBand` for the x-axis and `d3.scaleLinear` for the y-axis, with tick labels formatted using `d3.format`.