Ditto on the birds. If the crane doesn't count, then neither should the saltwater crocodile. The crocodile is way closer to the crane than it is to anything else on the list, phylogenetically speaking.
It doesn't really matter how close they might be or whether they had similar origins, birds are not reptiles according to the standard system of taxonomic classification which is what this quiz uses. The kingdom animalia includes the phylum chordata (vertebrates) which is divided into five distinct common classes: reptiles, birds, fish, amphibians and mammals.