Step 1: Policy adoption.
The first National Water Policy of India was adopted in 1975 to regulate the use and conservation of water resources.
Step 2: Analyzing the options.
(A) 1975: Correct — First adoption.
(B) 1982: Later revisions, not the first.
(C) 1987: Revised version.
(D) 2002: Much later revision.
Step 3: Conclusion.
The correct answer is (A) 1975.