Answer: A. Both routes to ethanol require a catalyst.
The addition reaction hydrates ethene with steam: \(\text{C}_2\text{H}_4 + \text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_5\text{OH}\). Conditions: 300 °C, 60 atm, with concentrated phosphoric acid as the catalyst.
The fermentation of glucose: \(\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_2\text{H}_5\text{OH} + 2\text{CO}_2\). Conditions: 30–35 °C, anaerobic, with yeast — specifically the enzyme zymase produced by yeast — acting as the biological catalyst.
Both processes therefore rely on a catalyst → option A.
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