A. The tapeworm is not metamerically segmented. Tapeworms belong to the phylum Platyhelminthes, which are characterized by a bilaterally symmetrical, flattened body without any segmentation. In contrast, centipedes, crayfish, and sharks are all metamerically segmented animals, meaning they have a body composed of repeated segments with similar organ systems. Centipedes belong to the phylum Arthropoda and have a segmented body with one pair of legs per segment. Crayfish belong to the phylum Arthropoda as well, and have a cephalothorax and an abdomen, both of which are made up of segments. Sharks belong to the phylum Chordata, and although their body segments are less apparent, they are still considered metamerically segmented due to their internal structure. Therefore, option A is the correct answer.