True statement regarding the alveolar epithelial cells:

Gas exchange occurs across type I pneumocytes. Option A is incorrect. Type II pneumocytes synthesize surfactant. When there is alveolar injury, type I cells degenerate and are replaced by type II cells. Type II cells are thus responsible for regeneration of epithelium. Lamellar inclusion bodies are the structures within which surfactant is present, in type II pneumocytes. These bodies then release surfactant by exocytosis. Type III pneumocytes act as chemoreceptors. Type I and type II pneumocytes exist in a ratio of 1:1. Option D is incorrect.