Casey, a personal training client, is attempting to perform the ball cobra exercise. What important cue should his personal trainer provide regarding Casey's hand position? Select one: O a. "Internally rotate both arms and point the thumbs into the air." b. "Externally rotate both arms and point the thumbs toward the ground." O c. "Internallv rotate both arms and point the thumbs toward the ground." d. "Externally rotate both arms and point the thumbs into the air