A mobile phone price area chart visualizes monthly cost trends over time. The D3 v5 code (using `scaleTime`, `scaleLinear`, `line`, `area`, and `curveBasis`) renders smooth lines and gray shaded regions beneath them, with labeled axes for month and cost. Data is loaded from a CSV file via `csv` and parsed with `d3.timeParse`. Axes include gridlines via `tickSize`, and the SVG output uses styled paths with bold tick labels.