I believe the correct answer is D. brumby. Koalas, wombats, and kangaroos are definitely native to Australia, but I don't think brumies are. Brumby is a type of a horse, and horses aren't native to Australia, but were rather brought and then raised there in the 18th century.
Scientific Thinkers didn't accept it immediately because its has no proof or lack of information that needed to be prove by all others scienctific thinkers
