The correct answer is option 2, Forest Owlet. The critically endangered species are those at the highest risk of extinction. Option 1, Gangetic Dolphin, is not critically endangered; it is classified as endangered. Option 3, White bellied heron, is also not critically endangered; it is classified as vulnerable. Option 4, The gyps Vulture, is not mentioned in the question, so we cannot determine its classification from the given options. However, it is worth noting that several species of vultures, including the White-rumped Vulture and Indian Vulture, are critically endangered due to factors like habitat loss and poisoning. Therefore, based on the information given in the question, the Forest Owlet is the only species listed that is confirmed to be critically endangered.