DIRECTIONS: Read the passage carefully infer and draw conclusions from the facts presented in the text. The toothbrush as we know it today was not invented until 1938. However, early forms of the toothbrush have been in existence since 3000 BC. Ancient civilizations used a "chew stick," which was a thin twig with a frayed end. These 'chew sticks' were rubbed against the teeth. The bristle toothbrush, similar to the type used today, was not invented until 1498 in China. The bristles were actually the stiff, coarse hairs taken from the back of a hog's neck and attached to handles made of bone or bamboo. Boar bristles were used until 1938, when nylon bristles were introduced by Dupont de Nemours. The first nylon toothbrush was called Doctor West's Miracle Toothbrush. Later, Americans were influenced by the disciplined hygiene habits of soldiers from World War II. They became increasingly concerned with the practice of good oral hygiene and quickly adopted the nylon toothbrush. Why were early toothbrushes most likely called "chew sticks"?

• A. because people chewed on them to help clean the teeth
• B. because they were chewed on by animals
• C. because they tasted better when chewed
• D. because people chewed them after using them