The correct answer is (d). Great Indian Bustard is a bird, while the other options are mammals.
A mammal is a warm-blooded vertebrate animal characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These animals are also characterized by having a four-chambered heart, a diaphragm muscle, and a skeleton made up of bones.
Duck-billed platypus is a semiaquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young.
Bats are the only mammals capable of true flight. They are also the second largest order of mammals, after rodents. Bats are found on every continent except Antarctica, and in every habitat on Earth, except for the open ocean.
Whales are a group of marine mammals that includes dolphins and porpoises. They are the largest animals on Earth, and some species can grow up to 100 feet long. Whales are divided into two groups: toothed whales and baleen whales. Toothed whales, such as dolphins and orcas, use their teeth to catch prey, such as fish and squid. Baleen whales, such as humpback whales and blue whales, use baleen plates to filter food from the water.