The answer is c. the head and thorax region.
The word cephalothorax is derived from two Greek words - cephalon, meaning head, and thorax. So, it is a fusion of these two body parts, and it is characteristic for chelicerates (scorpions, spiders,...) and crustaceans (crabs, lobsters, shrimps,...) . Cephalothorax is unsegmented and rigid and it is easy to differ it from the abdomen.
