Gaseous Exchange in Alveoli

Steps:

• Identify key principles: Gas exchange occurs via diffusion across thin alveolar walls, driven by partial pressure gradients.
• Evaluate statement 1: Confirms oxygen moves from high concentration in alveoli to low in blood.
• Evaluate statement 2: Confirms CO2 moves from high concentration in blood to low in alveoli.
• Evaluate statement 3: Notes alveoli's large surface area and moist lining enhance diffusion efficiency.

Why D is correct:

• All three statements align with Fick's law of diffusion, which states rate depends on surface area, thickness, and concentration gradient.

Why the others are wrong:

• A excludes 3, but large surface area is essential for efficient exchange.
• B excludes 2, but CO2 diffusion from blood to alveoli is a core process.
• C excludes 1, but O2 diffusion into blood is fundamental.

Not enough information on exact statements, but D assumes all are accurate.

Final answer: D