If nothing was unclear or difficult, say so. Skip questions about steps you did not experience; use not applicable where appropriate.

Which label was unclear?
How did you connect colors to categories?
What explanation was missing?

Author notes / illustrative keys where applicable:
1. An unclear legend label identifies a series or category that readers cannot interpret confidently. Clarify the measured variable and actual category meaning.
2. The color-category connection reveals whether readers can identify series through the legend and labels. Provide accurate additional identifiers where appropriate, without treating color differentiation alone as proof of accessible or correct interpretation.
3. A missing explanation identifies the contextual link readers need between legend entries and the visual marks. Use accurate labels and additional identifiers rather than relying on color alone.