Correct Option: C

Tapeworms are flat segmented worms that live in the intestines of some animals. Animals can become infected with these parasites when grazing in pastures or drinking contaminated water. Eating undercooked meat from infected animals is the main cause of tapeworm infection in humans. The adult tapeworm is usually a whopping 15 to 30 feet long (4.5 to 9 meters) and lives in the small intestine. An infected person usually has only one or two worms. The tapeworms use their head, called the scolex, to attach themselves to the intestinal wall.