Active transport moves substances against their concentration gradient using energy

Steps:

• Recall active transport definition: requires energy to move particles from low to high concentration.
• Examine each option for direction of movement.
• Check examples: ion uptake by root hairs is active (against gradient for minerals); water uptake is passive osmosis (high to low water potential).
• Match: only low-to-high with ion example fits active transport.

Why D is correct:

• It matches the definition of active transport, which pumps ions like minerals from soil (low concentration) to root cells (high concentration) using ATP energy.

Why the others are wrong:

• A: Describes passive diffusion (high to low, no energy); ion uptake example is incorrect for this.
• B: No information provided, so cannot apply.
• C: Direction is correct (low to high), but water uptake example is passive osmosis, not active.

Final answer: D