Explanation:

- Real flow refers to the movement of goods and services in an economy. It illustrates how these things are exchanged in markets.

- Option 1: Flow of Goods

- It is included in real flow as it involves the physical movement of goods.

- Option 2: Flow of Services

- Also part of real flow, services are intangible yet vital contributions to the market exchange.

- Option 3: Both (a) and (b)

- This option includes both the flow of goods and services.

- Correct Answer: It accurately captures the complete essence of real flow.

- Option 4: None of these

- Incorrect, as options 1 and 2 are part of the real flow.