This interactive visualization displays prescription drug expenditure data from the Medical Expenditure Panel Survey, plotting annual out-of-pocket costs across gender categories. A color legend encodes gender groups using d3.scaleOrdinal with schemeCategory10 colors; hovering over legend items filters the scatter plot marks via d3.selection join operations, dimming non-matching points to 20% opacity. The scatter plot uses d3.scaleLinear for both axes and d3.axisLeft/axisBottom for tick marks. Data loads asynchronously from a CSV file and is parsed with d3.csvParse.