Which visualization type would most benefit from the use of Reference lines?

The use of reference lines is particularly beneficial in line charts because they provide a clear way to visualize important thresholds, goals, or trends in conjunction with the data being represented. Reference lines can indicate averages, targets, or historic values, allowing for immediate comparison against the actual data points plotted on the line chart. This enhances interpretation by visually guiding the viewer to significant insights, trends, or deviations.

In contrast, while other visualization types like bar charts and area charts can also incorporate reference lines, they typically do not utilize them to the same extent or for the same purposes as line charts. Pie charts are primarily focused on showing proportions of a whole and do not lend themselves to the concept of trend analysis that reference lines highlight. Hence, line charts are especially well-suited for incorporating such lines, making it easier to analyze performance over time or against specific benchmarks.