Explanation:

- The Finance Commission in India is established by the President every few years to define the financial relations between the central government and the individual state governments.

- The 15th Finance Commission was constituted by the President of India in November 2017.

- Its primary purpose is to make recommendations on the distribution of tax revenues between the union and the states.

- Correct Answer: Option 4 - five years

- It is mandated to cover a five-year duration (2020-2025).

- Other options like three, six, or four years do not align with the typical duration for which Finance Commissions are formed in India.