Explanation:

- Option:1, 1879

- Incorrect. By this time, India was still under British rule with no significant political movement regarding the formation of INC.

- Option:2, 1877

- Incorrect. During this time, the British Empire was focused on other administrative and geopolitical concerns in India.

- Option:3, 1875

- Incorrect. There were socio-political reform movements, but the INC was not established in this year.

- Option:4, 1885

- Correct. The Indian National Congress was established in this year. It was a pivotal moment in India's political history, as the organization played a critical role in the independence movement.

- Correct Answer: 1885