What must contract to cause a person's elbow to straighten?
Sextant Two pairs Muscles bones body parts Eyelids The knee joint The sphincter
A B C D E F G H
What must contract to cause a person's elbow to straighten? (A) Sextant (B) Two pairs (C) Muscles (D) bones (E) body parts (F) Eyelids (G) The knee joint (H) The sphincter