This interactive line chart displays price trends across months, letting users switch between two price columns via a dropdown menu. The visualization redraws the line with a smooth basis curve and animated transition whenever a new column is selected. Built with D3 v5, it uses `scaleTime` and `scaleLinear` for axes, `axisBottom` and `axisLeft` for tick marks, and a custom `dropdownMenu` component to handle user input. The data is loaded from an external CSV file, with month values parsed as dates and price strings converted to numbers.