Which visualization type is best for showing a trend over time?

• A. Bar chart
• B. Scatter plot
• C. Line chart
• D. Heatmap

Answer: (C)

Line charts are best for showing a trend over time because they place time on a continuous axis and connect successive data points with a line. This makes the direction of change (up or down) and the rate of change easy to see at a glance, so you can spot overall trends, seasonal patterns, and cycles over the period being examined.

Bar charts emphasize discrete values at specific points in time, which can obscure how values rise or fall from one period to the next. Scatter plots illustrate the relationship between two variables and aren’t designed to convey a sequence over time. Heatmaps show magnitude using color across a grid, which is great for spotting patterns across two dimensions but doesn’t naturally convey a smooth, chronological trend as clearly as a line chart does.