Which statement best summarizes the primary result of particulate smoke settling on lung surfaces after repeated inhalation?

• A. Particulates chemically convert to carbon monoxide and block oxygen transport.
• B. Particulates injure cilia causing them to stop functioning for several days. 
• C. Particulates accumulate as tar that darkens and coats the bronchi and alveoli.
• D. Particulates are rapidly metabolized into harmless water-soluble compounds.

Answer: (C)