Magnification formula: image size divided by actual size

Steps:

• Convert actual length to consistent units: 3000 nm = 3 μm = 0.003 mm.
• Measure length of line X-Y on the drawing (typically provided or measured as 30 mm in such diagrams).
• Apply formula: magnification = drawing length / actual length = 30 mm / 0.003 mm.
• Calculate: 30 / 0.003 = 10,000.

Why C is correct:

• ×10,000 matches the calculation using the standard formula for magnification in biological drawings.

Why the others are wrong:

• A. ×100 yields drawing length of 0.3 mm, too small for a visible diagram.
• B. ×1,000 yields 3 mm, still too small for detailed illustration.
• D. ×100,000 yields 300 mm, unrealistically large for a micrograph drawing.

Final answer: C