When these ligaments or folds come together, they prevent food from entering the lower respiratory tract.

A) Vocal folds
B) Vestibular folds
C) Cricothyroid ligaments
D) Epiglottic folds
E) Both "Vocal folds" and "Vestibular folds" are correct.

Both the vocal folds (also known as vocal cords) and the vestibular folds (false vocal cords) are involved in protecting the airway during swallowing. The vocal folds are better known for their role in sound production, but both sets of folds can close to prevent food from entering the lower respiratory tract.