Which of the following National Parks is unique in being a swamp with floating vegetation that supports a rich biodiversity?

1. The question asks to identify a National Park that is unique for being a swamp characterized by floating vegetation, supporting rich biodiversity. 2. Keibul Lamjao National Park, located in Manipur, India, on Loktak Lake, is famously the world's only floating national park. 3. Its ecosystem is characterized by 'phumdis', which are heterogeneous masses of vegetation, soil, and organic matter at various stages of decomposition, floating on the lake surface. This unique floating vegetation forms a swamp-like habitat. 4. This park supports a very rich biodiversity, including the critically endangered Sangai deer (Manipur brow-antlered deer), which is endemic to this park. 5. (A) Bhitarkanika National Park in Odisha is known for its mangrove forests and saltwater crocodiles. 6. (C) Keoladeo Ghana National Park in Rajasthan is a famous bird sanctuary, primarily a wetland ecosystem but not characterized by large-scale floating vegetation swamps. 7. (D) Sultanpur National Park in Haryana is also a bird sanctuary centered around a lake/wetland. 8. Therefore, Keibul Lamjao National Park (B) fits the description perfectly.