6. Select the sentence that has no errors

 Select the sentence that has no errors

6.

Bill's twenty-three year old son, who just came back from Greece, is undergoing physical therapy for the break in his femur-bone.

Bill's twenty-three year old son--who just came back from Greece, is undergoing physical therapy for the break in his femur.

Bill's twenty three year-old son is under-going physical therapy for the break in his leg, who just got back from Greece.

Bill's twenty-three-year-old son--who just came back from Greece--is undergoing physical therapy for the break in his femur.