Which graph is best for showing trends over time?

A line graph is the most effective choice for illustrating trends over time. This is primarily due to its ability to connect individual data points with a continuous line, which clearly depicts changes and trends across a specified period. The visual representation of data in a line graph allows viewers to easily recognize upward or downward trends, cycles, and patterns, making it an ideal tool for time series data.

In contrast, other types of graphs serve different purposes. Column and bar graphs are typically used for comparing discrete categories rather than showing changes over time. They can illustrate the magnitude of different groups but do not effectively convey a sense of continuity or progression. Pie graphs are designed to display parts of a whole at a single point in time, which makes them unsuitable for visualizing trends. Thus, for analyzing how data evolves, especially over a series of intervals, the line graph is the superior option.