Step 1: Understanding the Concept:
A unitary system of government is one where a single, central government holds all the power. Any sub-national units (like regions or provinces) only have powers that the central government chooses to delegate. This is in contrast to a federal system, where power is divided between a central government and state governments by a constitution.
Step 2: Detailed Explanation:
\[\begin{array}{rl} \bullet & \text{Great Britain (UK): It is a classic example of a unitary state. The UK Parliament in London is sovereign, and it has delegated some powers to devolved assemblies in Scotland, Wales, and Northern Ireland, but it can theoretically take those powers back.} \\ \bullet & \text{France: It is a highly centralized unitary republic.} \\ \bullet & \text{China: It is a single-party state governed by the Communist Party and has a unitary system of government.} \\ \end{array}\]
Since all three countries have unitary systems of government, the correct answer is "All of these".
Step 3: Final Answer:
Great Britain, France, and China all have a Unitary Government system.