question: A person's elbow straightens when muscles antagonistic to what contract?
choices.text: backbones hamstring bones Two pairs biceps body impulses abdominal muscles
choices.label: A B C D E F G H
formatted_question: A person's elbow straightens when muscles antagonistic to what contract? (A) backbones (B) hamstring (C) bones (D) Two pairs (E) biceps (F) body (G) impulses (H) abdominal muscles