Unit Conversion and Division for Cell Count Steps:

• Convert line length to micrometers: 1 cm = 10,000 μm = 10^4 μm.
• Eukaryotic cell diameter = 1.5 μm; maximum number = 10^4 μm / 1.5 μm ≈ 6,667 = 6.7 × 10^3 cells.
• Prokaryotic cell diameter = 7.5 μm; maximum number = 10^4 μm / 7.5 μm ≈ 1,333 = 1.3 × 10^3 cells. Why C is correct:
• Matches the calculated counts using consistent μm units and simple division for linear fit. Why the others are wrong:
• A: Incomplete exponents; does not specify full values.
• B: Underestimates both by factor of 10, likely from incorrect diameter (e.g., 15 μm and 75 μm).
• D: Overestimates both by factor of 10, likely from unit error (e.g., treating as nm without conversion).

Final answer: C