PATHOLOGY

Detailed explanation-1: -Answer and Explanation: The esophagus is not a structure of the respiratory system. This is consistent with answer choice “a". Instead, this is a structure of the gastrointestinal tract which allows food to travel from the mouth to the hollow organ named the stomach.

Detailed explanation-2: -Arteries are the blood vessels that help in carrying blood to different parts of the body and they are a part of the circulatory system whereas trachea, bronchi, nasal cavity are the parts of the respiratory system.

Detailed explanation-3: -Windpipe (trachea) Large airways (bronchi) Small airways (bronchioles) Lungs.

Detailed explanation-4: -Heart is not a part of respiratotory system. It is the part of circulatory system. Other all are the part of respiratory system.