(a) Has C-shaped rings

(b) It is covered by epiglottis

(c) It splits into the right and left lungs

(d) None of the above

(a) Respiration

(b) External respiration

(c) Cellular respiration

(d) None of the above

(a) 1 billion

(b) 800 million

(c) 500 million

(d) 1500 million

(a) Cilia

(b) Bronchioles

(c) Hairs in the lungs

(d) All of the above

(a) Alveoli

(b) Bronchus

(c) Bronchioles

(d) All of the above

(a) Oxygen

(b) Hydrogen

(c) Carbon dioxide

(d) None of the above

(a) Trachea

(b) Diaphragm

(c) The lungs

(d) All of the above

(a) It is controlled by the bronchioles

(b) It is controlled by the pulmonary arterioles

(c) It is controlled by the alveolar-capillary network

(d) It is controlled by the neurons, located in the medulla and pons

(a) Hilum

(b) Pleura

(c) Mediastinum

(d) Thoracic cage

(a) Alveoli

(b) Pharynx

(c) Larynx

(d) Trachea