For Using electrolysis to extract metals, which ion focus answer best supports this Unit 4.4 objective: Explain why carbon anodes are gradually used up during aluminium extraction?

The correct option is They are gradually used up. - correct ion focus for aluminium extraction.

The correct option is They are gradually used up. - correct ion focus for aluminium extraction. They are gradually used up. - correct ion focus for aluminium extraction is correct because it directly supports the approved learning objective to explain why carbon anodes are gradually used up during aluminium extraction. This ion focus variant asks students to separate aluminium extraction from similar Unit 4.4 chemical-change ideas. The reasoning belongs to Using electrolysis to extract metals within Electrolysis, so it should not be confused with nearby ideas about acids, alkalis, bases, oxidation, reduction, displacement, reactivity, electrolysis, electrodes, ions, pH, or salt preparation unless those are named in the objective. Use the focus term aluminium extraction to keep the answer aligned with AQA GCSE Chemistry 8462 Unit 4.4 Chemical changes. Keep acid, alkali and base distinct; keep oxidation and reduction distinct; do not mix reduction with displacement; keep electrolysis separate from electroplating; distinguish anode from cathode, positive ions from negative ions, oxidation state from ionic charge, and strong acid from concentrated acid. The other options are weaker because they either use the wrong reaction type, wrong ion, wrong electrode, wrong acid-base distinction, vague wording, or the wrong chemical-change context.