Ratio of Root Diameter to Vascular Tissue Diameter

Steps:

• Measure the root diameter (excluding root hairs) from the diagram: 40 cm.
• Measure the diameter of the vascular tissue and endodermis: 22 cm.
• Form the ratio: root diameter : vascular diameter = 40 cm : 22 cm.
• Confirm units are consistent and no simplification is required for the simple ratio.

Why B is correct:

• The diagram provides measurements in centimeters, directly matching 40 cm : 22 cm as the ratio per standard biological scaling for root cross-sections.

Why the others are wrong:

• A uses millimeters, inconsistent with diagram units.
• C omits units, failing to specify the scale from the diagram.
• D is incomplete and provides no ratio.

Final answer: B