question: wolves warn other wolves by using different what?
choices.text: backbones parties hormones colors expression antigens several pitches
choices.label: A B C D E F G H
fact2: Wolves communicate with each other using the different pitches of their howl.
combinedfact: wolves warn other wolves by using different pitches
formatted_question: wolves warn other wolves by using different what? (A) backbones (B) parties (C) hormones (D) colors (E) expression (F) antigens (G) several (H) pitches