The structure which prevents the entry of food into respiratory tract is:
The correct option is D Epiglottis
The epiglottis is a flap-like structure made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. The main function of the epiglottis is to close off the windpipe during eating which prevents the entry of the food into the respiratory tract so that food is not accidentally inhaled. Hence option D is correct.