Alkenes Undergo Hydration with Steam Steps:

• Recall that alkenes contain a C=C double bond, making them reactive towards addition reactions.
• Identify hydration as an addition reaction where water (from steam) adds across the double bond to form alcohols.
• Apply to propene (C3H6): it reacts with steam under acidic conditions to yield propan-2-ol (C3H7OH).
• Eliminate other options by checking their factual accuracy against alkene properties.

Why C is correct:

• Propene, an alkene, undergoes electrophilic addition with steam (H2O) in the presence of a phosphoric acid catalyst, following Markovnikov's rule to form a secondary alcohol.

Why the others are wrong:

• A: Alkenes have two fewer hydrogens than alkanes (CnH2n vs. CnH2n+2), not four.
• B: Polyunsaturated fats contain multiple C=C bonds in fatty acid chains, not polymers.
• D: The general formula CnH2n applies to monoalkenes; dienes and polyenes have different formulas.

Final answer: C