Interpreting Shapes in Material Cross-Sections

Steps:

• View the photomicrograph as a 2D slice of the material's internal structure.
• Identify visible outlines: circular rings indicate transverse cuts of cylindrical elements.
• Rule out 3D inferences: "hollow tube" suggests longitudinal extent not shown in cross-section.
• Eliminate mismatched shapes: spheres appear circular but context points to tubular plant tissues like xylem.

Why C is correct:

• Cross-sections of tubular structures (e.g., xylem vessels) reveal circular profiles per microscopic anatomy definitions, confirming only observation 1.

Why the others are wrong:

• A includes 2 and 3, but 2 implies unseen 3D hollowness and 3 mismatches tubular context.
• B includes 2, which overinterprets the 2D view as a full tube.
• D selects only 3, ignoring evident circular outlines of cylinders, not spheres.

Final answer: C