Final answer:
True. Under certain conditions, the vocal folds act as a sphincter that prevents air passage.
Step-by-step explanation:
True. Under certain conditions, the vocal folds act as a sphincter that prevents air passage. The vocal folds, also known as the true vocal cords, are flexible white membranous folds attached to the larynx. When swallowing occurs, the pharynx and larynx lift upward, allowing the pharynx to expand and the epiglottis to swing downward, closing the opening to the trachea. This prevents food and beverages from entering the trachea, but it also prevents air from passing through.