This area chart visualizes the relationship between age and average calories burned, using a lightsteelblue filled area with a steelblue stroke. The visualization aggregates a lifestyle CSV dataset by computing the mean calories burned for each age value. Built with D3 v7, the code uses `d3.rollup` and `d3.mean` to group and summarize the data, then renders the result as an SVG path via the `d3.area()` generator. Linear scales for both axes, axis generators, and descriptive labels complete the chart.