(i) During inhalation, ribs move inward and diaphragm is raised
(ii) In the alveoli, exchange of gases takes place i.e., oxygen from
alveolar air diffuses into blood and carbon dioxide from blood
into alveolar air
(iii) Haemoglobin has greater affinity for carbon dioxide than
oxygen
(iv) Alveoli increase surface area for exchange of gases
(a) (i) and (iv) (b) (ii) and (iii)
(c) (i) and (iii) (d) (ii) and (iv)
