Explanation:

- Correct Answer: Option 4 - Amit Shah

- Amit Shah, who was the Union Home Minister in January 2020, chaired the sixth meeting of the Island Development Agency in New Delhi. The Island Development Agency (IDA) is responsible for the holistic development of islands in India.

- Option 1: Narendra Modi

- Narendra Modi is the Prime Minister of India. While he is the head of the government, he typically does not chair specific agency meetings such as the Island Development Agency.

- Option 2: Nirmala Sitharaman

- Nirmala Sitharaman serves as the Finance Minister. Her role primarily involves matters related to finance and the economy rather than island development.

- Option 3: Nitin Gadkari

- Nitin Gadkari has held portfolios like Road Transport and Highways. While infrastructure development is within his domain, the IDA meeting in January 2020 was not chaired by him.