Answer
b. hyperextension
Work Step by Step
Bending backwards at the waist is hyperextension.
Rotation would be turning at the waist.
Flexion is bending forward at the waist.
The waist can't do dorsiflexion (only feet) or abduction.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.