(A) - (III), (B) - (IV), (C) - (I), (D) - (II) -> Let's analyze each scenario:
(A) Both demand and supply shift leftward: Demand ↓ (price↓, quantity↓) + Supply ↓ (price↑, quantity↓) = Quantity definitely decreases, but price effect is ambiguous (depends on relative magnitudes). Matches (III).
(B) Both demand and supply shift rightward: Demand ↑ (price↑, quantity↑) + Supply ↑ (price↓, quantity↑) = Quantity definitely increases, but price effect is ambiguous. Matches (IV).
(C) Demand shifts leftward, supply shifts rightward: Demand ↓ (price↓, quantity↓) + Supply ↑ (price↓, quantity↑) = Price definitely decreases, but quantity effect is ambiguous. Matches (I).
(D) Demand shifts rightward, supply shifts leftward: Demand ↑ (price↑, quantity↑) + Supply ↓ (price↑, quantity↓) = Price definitely increases, but quantity effect is ambiguous. Matches (II). -> correct