ACT English Practice Question

Read the following excerpt and consider the bolded portion. Which choice makes the sentence most grammatically acceptable? Pang Xiong Sirirathasuk Sikoun is a master of paj ntaub, or “flower cloth” embroidery, the most difficult of the **century’s-oldest** Hmong needlework arts.

1. A.No Change
2. B.centuries-old
3. C.centuries’-old
4. D.century’s-old