Step 1: Creola bodies are clusters of ciliated columnar epithelial cells that are shed from the bronchial mucosa and appear in the sputum. They are a histopathological marker of bronchial asthma.
Step 2: In asthma, chronic airway inflammation damages and sloughs the surface epithelium, so these epithelial cell clusters (Creola bodies) turn up in the sputum, pointing to option a.
Step 3: The same asthmatic sputum classically also shows Charcot-Leyden crystals, Curschmann's spirals and eosinophils. Chronic bronchitis, emphysema and bronchiectasis are not characterised by Creola bodies, so options b, c and d are incorrect.