Scatter plot is a graph designed to show
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The variation is testing results
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The variation in process
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Relationship between two changing variables
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Relationship between expected and actual results
A scatter plot is a graph that displays two variables on perpendicular axes to show their relationship or correlation. Each point represents one observation with values for both variables, revealing patterns like positive correlation, negative correlation, or no relationship. Options A and B incorrectly describe process variation; option D describes comparison testing.
A scatter plot (or scatter diagram) plots paired data points on an X-Y axis to visually reveal whether and how two variables are related — e.g., correlation, trend, or lack thereof. That makes 'Relationship between two changing variables' the correct definition. It is not specifically about test/process variation over time (that's a run chart or control chart), and it's not about comparing expected vs. actual results (that would be a different quality-control tool, like a check sheet or Pareto analysis). The distinguishing feature of a scatter plot is exactly its use for examining correlation between two variables.