Explanation:

- The Global Shelter Strategy (GSS) was a global initiative by the United Nations to promote housing for all by the year 2000.

- As a national response, India formulated the National Housing Policy (NHP).

- Option 1 (1985): This is before the GSS and is not correct.

- Option 2 (1986): This is also prior to the main discourse around national frameworks.

- Option 3 (1987): Though discussions intensified in this period, the policy was not formally announced yet.

- Option 4 (1988): This is the correct answer. The National Housing Policy (NHP) was officially announced by the Government of India in 1988 as a follow-up to the GSS.