DA0-002 Visualization and Reporting Practice Question
A data analyst is presenting a story to executives about a decline in sales. The analyst wants to show the key events that led to the decline, such as a product recall and a competitor's launch. Which storytelling technique should be used?
⚠ Common exam trap
The trap is choosing a chart type that shows composition or variance (pie, waterfall, treemap) when the question is about correlating discrete events with a time-series trend — only time-aligned annotation on a line chart tells that story.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Annotating the line chart with event markers
Annotating a line chart with event markers ties specific business events (product recall, competitor launch) to the points in time where sales changed, making the causal narrative visually explicit. This is the standard storytelling technique for explaining a trend's drivers over time.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Using a pie chart to show current market share
Why it's wrong here
A pie chart shows proportional composition at one point in time, so it cannot sequence the recall and competitor launch as causal events. It is tempting because pie charts are the correct choice when the goal is comparing parts of a whole, such as current market share by competitor.
- ✗
Adding a waterfall chart to show incremental changes
Why it's wrong here
A waterfall chart quantifies cumulative numeric contribution between a start and end total, not the chronological sequence of discrete events. It is tempting because it suits variance decomposition, such as explaining which cost categories drove a profit change, but the stem asks for a narrative timeline of recall and competitor launch.
- ✓
Annotating the line chart with event markers
Why this is correct
Event markers placed on the line chart tie each annotation to the exact point in time when the recall and competitor launch occurred, letting executives see cause and effect. This satisfies the requirement to show the key events driving the sales decline.
- ✗
Using a treemap to show hierarchical proportions
Why it's wrong here
A treemap encodes hierarchical part-to-whole proportions by nested rectangle area, so it cannot express chronological ordering of events. It is tempting because it suits showing which product categories dominate revenue, but the stem requires sequencing a recall before a competitor launch, which a timeline or annotated narrative delivers.
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Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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