Pupil Dilation in Dim Light

Steps:

• In dim light, the pupil dilates to allow more light into the eye for better visibility.
• Compare diagrams by pupil size: larger pupil indicates dim light adaptation.
• Eliminate options with small pupils or unrelated features like lens curvature.
• Select the diagram showing a wide-open pupil with rays entering broadly.

Why B is correct:

• Diagram B depicts a dilated pupil, which maximizes light entry in low illumination per the pupillary light reflex mechanism.

Why the others are wrong:

• A: Shows constricted pupil, typical for bright light to reduce glare.
• C: Illustrates lens accommodation for near vision, irrelevant to light levels.
• D: Depicts inverted image formation without pupil adjustment, not specific to dim conditions.

Final answer: B