Galvanization's Protective Mechanisms

Steps:

• Identify statement 1: Zinc coating acts as a physical barrier, blocking oxygen and water from reaching iron, preventing rust.
• Evaluate statement 2: Zinc is more reactive than iron (higher in reactivity series), so it oxidizes preferentially if scratched, providing sacrificial protection.
• Examine statement 3: This statement is incomplete and grammatically unclear, failing to convey a complete idea about zinc's role when scratched.
• Conclude correct statements: Only 1 is fully accurate; 2 is true but paired with flawed 3 in options.

Why A is correct:

• A selects only statement 1, matching the barrier protection definition in galvanization without including incomplete or misleading claims.

Why the others are wrong:

• B includes 2, but ignores 3's incompleteness, overselecting valid sacrificial action.
• C selects 2 and 3, but 3 is not a coherent statement.
• D includes all, but 3 is invalid due to its unfinished phrasing.

Final answer: A