The correct answer is option 4 - Union of States. Article 1 of the Indian Constitution declares India as a Union of States.

Option 1 - Federal State: This refers to a system of government where power is divided between a central government and its constituent states. However, India is not a fully federal state because certain powers are concentrated at the center.

Option 2 - Quasi-Federal State: This refers to a system that has some characteristics of both a federal and a unitary state. While India does have some characteristics of a quasi-federal state, it is more accurately described as a union of states.

Option 3 - Unitary State: In a unitary state, power is concentrated at the central government and there is little or no power given to regional or constituent states. This does not accurately describe India`s system of government.

Therefore, the correct answer is option 4 - Union of States.