Efficient endpoints on the PPC

Steps:

• Identify the PPC as the curve showing maximum output combinations with full resource use.
• Locate endpoints: one maximizes computers (all resources to computers), the other maximizes food (all to food).
• Confirm W and X as intercepts representing these extremes.
• Verify interior points like Y and Z show trade-offs, not maxima.

Why A is correct:

• PPC endpoints (W and X) define absolute maxima for each good under full employment, per the law of increasing opportunity cost.

Why the others are wrong:

• B: X and Y include an interior point, not both maxima.
• C: Y and Z are both interior, showing balanced but not extreme outputs.
• D: Z and W mix interior and one endpoint, missing full maxima pair.

Final answer: A