Match the molecule with its role in respiration.
| Column I | Column II |
|---|---|
| (a) Glucose | (i) The ultimate electron acceptor in aerobic respiration |
| (b) Pyruvate | (ii) The key product of glycolysis |
| (c) Oxygen | (iii) The substrate that enters glycolysis |
| (d) Water | (iv) A product of the ETS |