This line chart visualizes the Bitcoin Price Index from December 2017 to April 2018, using historical data fetched from the CoinDesk API. The chart displays price trends over time with a red line, clearly showing fluctuations in Bitcoin’s value across the four-month period. The visualization is built with D3.js v4, using `d3.scaleTime` and `d3.scaleLinear` for the axes, `d3.line` for the path, and `d3.axisBottom` and `d3.axisLeft` for the labeled axes. The data is parsed from JSON into date-value pairs, and the SVG rendering includes styled gridlines, tick labels, and an axis label for price in dollars.