Equilibrium in Circular Flow Model

Steps:

• Recall the circular flow model: income flows between households and firms, with injections (investment, government spending, exports) adding to the flow and withdrawals (savings, taxes, imports) removing from it.
• In an open economy, equilibrium occurs when total planned injections equal total planned withdrawals, balancing the economy without unintended inventory changes.
• Analyze choices: A focuses only on investments, ignoring other flows; C limits to households and taxes; D equates only trade components.
• Confirm B matches the core condition for equilibrium in the model.

Why B is correct:

• Equilibrium requires planned injections (I + G + X) to equal planned withdrawals (S + T + M), ensuring aggregate demand equals aggregate supply per the circular flow identity.

Why the others are wrong:

• A: Ignores savings, taxes, imports, and exports; equilibrium involves all injections and withdrawals.
• C: Only partial withdrawal (taxes) versus household spending; misses full flow balance.
• D: Balances trade but neglects domestic injections like investment and government spending.

Final answer: B