What does a line chart typically represent?

A line chart is primarily used to display data points in a time series, showing how values change over time. This visualization connects individual data points with lines, allowing viewers to easily track trends, fluctuations, and patterns across various time intervals. By using a continuous line, the chart facilitates the comparison of values at different moments, helping users identify increases, decreases, and overall trends effectively.

In contrast, other options describe different types of data representation. For example, a single value for a day would imply a more static or snapshot view of data, lacking the continuous change that a line chart illustrates. Comparing related values might be better represented in formats such as bar charts or scatter plots, which emphasize the relationship rather than a time-dependent change. Lastly, displaying a percentage of a whole typically relates to pie charts or similar representations that show parts of a whole rather than trends over time. Therefore, option B is the most accurate representation of what a line chart accomplishes.