A line chart visualizes a single time series of numeric measurements recorded daily from July 20 to August 2, 2019, with the y-axis labeled "Frequency." The chart uses d3.v5 with an SVG viewBox, applying d3.scaleTime and d3.scaleLinear for axes, d3.line for the path, and d3.timeFormat for date ticks. The data comes from a local CSV file parsed with d3.timeParse, and the single series is styled with a solid orange stroke via CSS.