Which structure is labeled x in the diagram below?                                                               ribosomelipid envelopeprotein tailcapsid proteinmark this and return

You find a fossil that you are sure shows evidence of bipedalism. you know this because which of the following anatomical traits is present? a. thighbones that angle in toward the knees b. a narrow pelvis c. opposable hallux d. posterior position of the foramen magnum