Final answer:
Cilia in the respiratory system actively expel foreign matter by swallowing, sneezing, and coughing, but not by the act of breathing itself.
Step-by-step explanation:
The cilia in the nasal cavity, trachea, and bronchi are responsible for trapping and removing foreign matter from the body. These microscopic, hair-like projections move in a coordinated sweeping motion, pushing the mucus and trapped particles upward toward the throat. The actions performed by cilia to expel foreign matter include swallowing, sneezing, and coughing. Therefore, the correct answer to the question, 'Which of the following does the cilia not do to expel foreign matter from the body?' is C. breathing, as breathing does not directly contribute to the expelling of particles by cilia movement.