The option stating that "Statement-I is correct but Statement-II is incorrect" is valid because it reflects the ecological distribution of marsupials. Marsupials, such as kangaroos and koalas, are primarily indigenous to Australia and nearby islands, hence they are not naturally found in India (Statement-I). Statement-II is incorrect because marsupials are adaptable and can thrive in a variety of habitats, not limited to montane grasslands, and do not require the absence of predators for survival; many marsupials have evolved various strategies to coexist with predators in their ecosystems. This understanding highlights the importance of habitat diversity and adaptability in species survival, a concept fundamental to ecological studies as covered in UPSC materials.