The respiratory system is made up of trachea, the lungs and the–

Correct option is A

Sol. The diaphragm is a dome-shaped muscular structure located beneath the lungs and is a critical component of the respiratory system. During inhalation, the diaphragm contracts and moves downward, creating space in the thoracic cavity for lungs to expand. It plays a direct role in breathing mechanics, unlike other options listed. Along with the trachea, bronchi, and lungs, the diaphragm is vital for effective respiration.
Explanation of each option:
· (a) Diaphragm – Correct. It is the primary muscle responsible for breathing, helping the lungs to inhale and exhale air by changing chest cavity pressure.
· (b) Pancreas – Incorrect. The pancreas is part of the digestive and endocrine systems, producing insulin and digestive enzymes, not involved in respiration.
· (c) Esophagus – Incorrect. The esophagus is a food pipe, part of the digestive system, and runs parallel to the trachea but does not assist in breathing.
· (d) Liver – Incorrect. The liver is a digestive gland located under the diaphragm. It performs metabolic functions but is not part of the respiratory system.