What structure moves debris-laden mucus toward the pharynx?

Cilia are microscopic hair-like structures that line the respiratory tract and play a crucial role in clearing mucus and debris from the airways. These structures are capable of coordinated, wave-like movements which propel mucus upward toward the pharynx. This process is vital for maintaining respiratory health, as it helps to trap and remove inhaled particles, pathogens, and other contaminants out of the airways. The mucus, combined with trapped debris, is then swallowed or expelled, preventing infections and maintaining clear air passages.

Other options do not predominantly perform this specific function. Filaments do not contribute significantly to the movement of mucus in the respiratory system. Mucosal layers refer more to the linings that produce mucus rather than structures that actively move it. Thus, the action of cilia in the respiratory system is essential for the movement of debris-laden mucus.