Calculating virus length from micrograph magnification

Steps:

• Measure the virus length on the micrograph (e.g., 0.66 mm or 660 μm).
• Convert measured length to meters: 660 × 10^{-6} m.
• Divide by magnification factor: actual length = measured length / 30,000.
• Compute: (660 × 10^{-6}) / 30,000 = 22 × 10^{-9} m.

Why A is correct:

• Matches the calculation using the standard formula for actual size: measured size divided by magnification, yielding 22 nm (22 × 10^{-9} m), a typical virus dimension.

Why the others are wrong:

• B duplicates A but is listed separately; select A as specified.
• C is 10 times too small (2.2 nm), underestimating by ignoring correct measurement conversion.
• D duplicates C, repeating the underestimation error.

Final answer: A