Scarcity rises from lower supply or higher demand

Steps:

• PPC represents maximum efficient output; left shift reduces total goods producible.
• Population growth increases demand for fixed goods output.
• Scarcity is goods relative to wants; both factors heighten it.
• Option A combines reduced supply and higher demand, making goods scarcer.

Why A is correct:

• PPC left shift cuts production frontier (by definition, showing attainable output), while population rise boosts wants, increasing scarcity per economic scarcity law.

Why the others are wrong:

• B: PPC right shift expands output capacity, easing scarcity.
• C: Population decrease lowers demand, reducing scarcity.
• D: No changes in PPC or population keep scarcity stable or decreasing.

Final answer: A