This visualization displays box plots of medical insurance charges grouped by age decade and smoker status, revealing higher costs for smokers across all age groups. The chart uses D3 v7 with the d3-rosetta utility library, computing quartiles, medians, and whiskers from the CSV dataset. Each age decade shows paired box plots for smokers and non-smokers with interactive tooltips displaying summary statistics, alongside axis labels, a legend, and sample counts rendered through modular rendering functions.