Which type of chart is typically used to represent data over a period of time?

The correct answer is a line chart, which is specifically designed to show trends or changes in data over time. Line charts plot data points on a graph and connect them with a line, making it easier to visualize how values fluctuate across a continuous time scale. This characteristic is particularly useful for tracking progress, identifying patterns, or forecasting future trends.

In contrast, pie charts represent data as parts of a whole at a single point in time and do not effectively communicate changes over time. Bar charts can display changes over time but are typically better suited for comparing discrete categories rather than illustrating trends. Scatter plots are used to show the relationship between two variables but do not inherently convey temporal changes, as they do not connect data points in the same manner as line charts. Thus, line charts serve as the most effective visualization tool for depicting time-based data.