The correct answer is option 2, USA. A federal form of government refers to a system where power is divided and shared between a central government and various regional or state governments. In a federal system, each level of government has its own set of powers and responsibilities.

Option 1, China, does not have a federal form of government. China has a unitary form of government where power is concentrated in the central government.

Option 3, Cuba, also does not have a federal form of government. Cuba has a unitary socialist state where power is centralized in the Communist Party.

Option 4, Belgium, does enjoy a federal form of government. The country is divided into regions and communities, each with its own government, alongside a central government.

So, the correct answer is option 2, USA, as it has a federal form of government.