Correct Response: C. Cilia are hairlike extensions of the cell membrane of specialized cells that are found in the bronchi and bronchioles of the lungs. They have an upward sweeping motion that assists in moving dust and other particles that have entered the lungs back out into the environment. The lining of the lungs has specialized cells called goblet cells (A) that produce secretions to trap dust and other particles that have entered the trachea. The lungs hold air that is brought in, and the body warms the air as it enters the lungs (B). Oxygen moves from cells that line the lungs' alveoli into the blood by diffusion (D). None of these processes require the use of cilia.
