34Gas ExchangeMedium1 markWhich statement is correct?AAlveoli have goblet cells to produce mucus to trap pathogens from the air.BCartilage in the bronchi keeps the bronchi open and allows air to flow through freely.CComplete rings of cartilage in the bronchioles make sure that air can reach the alveoli.DDuring exercise, muscles in the bronchioles and alveoli relax to allow a greater flow of air.Grade answerSolutionGrading criteria