Option 3: (A) - (II), (B) - (IV), (C) - (III), (D) - (I) -> The correct matching is: Marginal Propensity to Consume (MPC) = ΔC/ΔY which measures the change in consumption for a unit change in income; Marginal Propensity to Save (MPS) = ΔS/ΔY which measures the change in savings for a unit change in income; Average Propensity to Save (APS) = S/Y which is the ratio of total savings to total income; Average Propensity to Consume (APC) = C/Y which is the ratio of total consumption to total income. Remember that 'Marginal' concepts use Δ (change/delta) while 'Average' concepts use total values. -> correct