Redox involves oxidation state changes Steps:

• Define redox as a reaction with electron transfer, shown by oxidation number shifts.
• Examine each option for reacting species and potential oxidation/reduction.
• Identify if metals, hydrogen, or other elements change oxidation states.
• Confirm the reaction producing a gas or displacing elements indicates redox.

Why B is correct:

• Sodium (oxidation state 0) reacts with ethanoic acid to form sodium ethanoate and H₂; Na oxidizes to +1, H reduces from +1 to 0, fitting the redox definition.

Why the others are wrong:

• A: Neutralization (CH₃COOH + NaOH → CH₃COONa + H₂O) involves proton transfer, no oxidation state changes.
• C: Two acids (ethanoic + HCl) do not react; no electron transfer occurs.
• D: Ester hydrolysis (CH₃COOCH₂CH₃ + HCl → CH₃COOH + C₂H₅OH) is acid-catalyzed, with no redox changes.

Final answer: B