Dugong is a marine mammal and is the correct answer. It is not a desert gazelle (option 1), which is a completely different animal found in arid regions. Dugongs are also not migratory raptors (option 3), which are birds of prey that migrate long distances. Additionally, dugongs are not saltwater crocodiles (option 4), which are reptiles and not mammals.

Dugongs, scientifically known as Dugong dugon, are large marine mammals that are found in shallow coastal waters of the Indian Ocean and the western Pacific Ocean, including the waters surrounding India. They are herbivorous creatures and are often referred to as "sea cows" due to their grazing habits and slow-moving nature. Dugongs have a streamlined body, a horizontal tail, and front flippers that resemble dug-out paddles. They feed on seagrass and are known to live up to 70 years. Dugongs are a vulnerable species and are protected under wildlife conservation laws. Their population is under threat due to activities such as habitat destruction, pollution, and hunting.