Emphysema damages alveoli, impairing oxygen diffusion

Steps:

• Both people have equal mass and exercise, so similar oxygen demand.
• Healthy person absorbs 22 cm³/min oxygen; emphysema patient only 12 cm³/min, showing reduced uptake.
• Emphysema destroys alveolar walls, reducing gas exchange surface area.
• This damage explains lower oxygen entry despite equal activity.

Why C is correct:

• Emphysema causes alveolar destruction, creating smaller, damaged alveoli that decrease diffusion surface area, limiting oxygen transfer per Fick's law of diffusion.

Why the others are wrong:

• A: Breathing rate may be similar; problem is alveolar exchange, not ventilation speed.
• B: Emphysema enlarges lungs via air trapping, increasing volume, not decreasing it.
• D: Alveoli enlarge in emphysema, but without damage emphasis, it ignores reduced efficiency from wall breakdown.

Final answer: C