Normative statements express value judgments on what ought to be

Steps:

• Identify normative statements as those involving opinions or prescriptions about policy or ethics.
• Distinguish from positive statements, which describe observable facts or testable relationships.
• Evaluate each option for subjective "should" language versus objective descriptions.
• Select the option that prescribes action rather than stating facts.

Why D is correct:

• Normative statements involve subjective judgments; "should be increased" prescribes a policy action based on values, not facts.

Why the others are wrong:

• A: Positive; states a historical fact about China's payments.
• B: Positive; describes a potential economic relationship testable by data.
• C: Positive; asserts an efficiency outcome in economic theory.

Final answer: D