Root hair features optimizing ion absorption

Steps:

• Identify key features: 1 (large surface area), 2 (thick cell wall), 3 (abundant mitochondria for active transport).
• Evaluate surface area: Increases contact with soil solution, boosting passive diffusion.
• Assess cell wall: Thick wall hinders ion passage, reducing efficiency.
• Confirm mitochondria: Supply ATP for active uptake against gradients.

Why B is correct:

• Features 1 and 3 align with diffusion and active transport principles, maximizing ion influx per Fick's law and ATP-driven pumps.

Why the others are wrong:

• A includes 2, but thick walls impede permeability.
• C omits 3, ignoring active transport's role in low-concentration soils.
• D excludes 1, neglecting surface area for initial ion capture.

Final answer: B