This line chart visualizes monthly customer spending across twelve months, with values rising from $200 in January to $550 in December. It uses D3.js v7 with an SVG rendering approach, employing `d3.scaleBand` for the monthly x-axis and `d3.scaleLinear` for the spending y-axis. The chart draws a monotone curve line via `d3.line()` with `curveMonotoneX`, marks each data point with circles, and labels the axes "Month" and "Spending ($)" using `d3.axisBottom` and `d3.axisLeft`. The sample dataset is defined explicitly in `index.js` and passed to a global `renderLineChart` function.