Final answer:
The epiglottis is the structure that keeps food and liquids from being swallowed into the lungs by closing the opening of the larynx during swallowing. Hence the correct option is A .
Step-by-step explanation:
The structure that keeps food and liquids from being swallowed into the lungs is the epiglottis. The epiglottis is a cartilaginous flap located at the back of the tongue that closes the opening of the larynx, or the entrance to the windpipe, during swallowing. This prevents food and liquids from entering the trachea and lungs, directing them instead to the esophagus.
For example, when you swallow a bite of food, the epiglottis flips down to cover the larynx, ensuring that the food passes into the esophagus and not the trachea. This helps protect the respiratory system from potential harm caused by inhaling foreign substances into the lungs. Hence the correct option is A .