Explanation:

Option-1 suggests that both the assertions are true, and that the reason (R) is the correct explanation for Assertion A. This isn`t valid because reason (R) is incorrect, thus it can`t be a correct explanation.

Option-2 asserts that both A and R are accurate but R doesn`t explain A. This might be a plausible choice if Reason (R) was correct because it doesn`t directly explain the launching of Central Rural Sanitation Programme.

Option-3 mentions that Assertion (A) is correct while Reason (R) is false. This is correct as the Central Rural Sanitation Programme was certainly initiated in 1986 to improve rural conditions in India, but sanitation is a state subject and not in the concurrent list of the Indian constitution.

Option-4 suggests that Assertion (A) is wrong while Reason (R) is right, which is incorrect as the Central Rural Sanitation Programme was indeed initiated in 1986.

The correct answer, therefore, is option 3: `A is true but R is false`.