Step 1: Understanding the Concept:
This question covers the fundamental definitions used to describe the movement of value through an economy.
Step 2: Detailed Explanation:
1. Real Flow: The physical movement of goods, services, and factor inputs between sectors (A matches i).
2. Monetary Flow: The exchange of money (wages, payments for goods) between sectors (B matches iii).
3. Injections: Variables like Investment, Govt Spending, or Exports that add money to the circular flow, thus strengthening economic activity (C matches iv).
4. Leakages: Variables like Savings, Taxes, or Imports that take money out of the circular flow, thus weakening economic activity (D matches ii).
Step 3: Final Answer:
The only option that correctly matches all four pairs is Option (A).