The correct answer is Option (4)-Snail

The organism that is NOT a vertebrate is: Snail

Snails belong to the phylum Mollusca and are not vertebrates. They are part of the class Gastropoda, which includes organisms with a soft body, often protected by a shell. Vertebrates, on the other hand, are characterized by having a backbone or spinal column composed of vertebrae. Fish, mammals, and birds are all examples of vertebrates, as they possess a vertebral column.