Section 3(2) of the Environment (Protection) Act, 1986 lists the Central Government's powers in separate numbered sub-clauses, and the question asks which specific power falls under sub-clause (ii).
Matching each listed power to its specific sub-clause confirms that quality-standard setting is what Section 3(2)(ii) covers.
Hence, the correct answer is Laying down standards for the quality of the environment in its various aspects.