This area chart visualizes the relationship between pet age in months and adoption fees in dollars, using a blue-filled area with orange hover dots. The dataset is loaded from a CSV file via `d3.csv`, and both quantitative scales are linear. The chart is rendered as SVG using D3 v7, with the `d3.area()` generator defining the region between the baseline and the data points. Interactive tooltips appear on mouse movement using D3 event handlers and the `d3.select` API, while axes are appended via `d3.axisBottom` and `d3.axisLeft`.