For The reactivity series, which acid-base focus answer best supports this Unit 4.4 objective: Identify which substance is oxidised and which is reduced in oxygen-transfer reactions?

The correct option is It loses oxygen - correct acid-base focus for which.

The correct option is It loses oxygen - correct acid-base focus for which. It loses oxygen - correct acid-base focus for which is correct because it directly supports the approved learning objective to identify which substance is oxidised and which is reduced in oxygen-transfer reactions. This acid-base focus variant asks students to separate which from similar Unit 4.4 chemical-change ideas. The reasoning belongs to The reactivity series within Reactivity of metals, 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 which 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.