This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
Hypoxemia in emphysema is due to all except- 
Select and explain. 
A. Destruction of alveoli, B. Anatomiacal dead space, C. Physiological dead space, D. Elastic recoil
B: Anatomiacal dead space
Answer: B: Anatomiacal dead space 
Explanation: Emphysema is characterised by destruction of gas-exchanging air spaces i.e.,the respiratory bronchioles,alveolar ducts,and alveoli.As a result,physiological dead space increases.Loss of elastic tissue,inflammation and fibrosis in airway wall result in premature airway closure,gas trapping,and dynamic hyperinflation leading to changes in pulmonary and chest wall compliance.As a result,elastic recoil is reduced. Reference:Harrison's medicine-18th edition,page no:2154.