Linear magnification is the ratio of image height to object height

Steps:

• Measure object height (h_o) from the scale diagram.
• Measure image height (h_i) from the scale diagram.
• Compute m = h_i / h_o.
• Diagram scales show h_i = 3 × h_o, so m = 3.0.

Why B is correct:

• By definition, linear magnification m = h_i / h_o for lenses, and the diagram's scaled heights yield exactly 3.0.

Why the others are wrong:

• A: 0.3 implies minification, contradicting the magnified image stated.
• C: 4.0 overestimates the height ratio in the diagram.
• D: 6.0 doubles the actual measured ratio.

Final answer: B