question: Ancestors of hagfish are thought to have been the earliest animals with what?
choices.text: fossil record antigens backbones antibodies arms feet hairs wings
choices.label: A B C D E F G H
fact2: Vertebrates are animals with backbones, such as horses.
combinedfact: Ancestors of hagfish are thought to have been the earliest animals with backbones
formatted_question: Ancestors of hagfish are thought to have been the earliest animals with what? (A) fossil record (B) antigens (C) backbones (D) antibodies (E) arms (F) feet (G) hairs (H) wings