Statement-I is correct. The Supreme Court of India has, in several judgments such as the Indra Sawhney case (1992) and M. Nagaraj case (2006), affirmed that reservation policies under Article 16(4) must be implemented while upholding the efficiency of administration, as mandated by Article 335. This establishes a constitutional limitation on the extent of reservations.
Statement-II is incorrect. Article 335 of the Constitution stipulates that the claims of Scheduled Castes and Scheduled Tribes in appointments shall be considered "consistently with the maintenance of efficiency of administration." However, the Article itself does not define the term 'efficiency of administration'. Its interpretation has been largely left to judicial pronouncements and executive understanding.
Options (a), (b), and (d) are incorrect because Statement-I accurately reflects the Supreme Court's position on the interplay between Article 16(4) and Article 335, making it correct. Statement-II, however, incorrectly asserts that Article 335 defines 'efficiency of administration', which is not the case. Therefore, any option suggesting Statement-II is correct, or Statement-I is incorrect, is invalid.