What can cause bronchitis?

Bronchitis can be caused by a variety of factors, making the second option the most accurate. Both bacterial infections and long-term exposure to irritants, such as smoke, pollution, and dust, contribute significantly to the development of bronchitis. Viral infections can also cause bronchitis, but the primary consideration for this question is the comprehensive view provided in option B, which encompasses both bacterial pathways and chronic exposure to harmful substances.

Long-term irritants lead to chronic bronchitis, characterized by persistent inflammation of the airways, while bacterial infections can lead to acute forms of bronchitis. This duality of cause—both infectious and environmental—captures the main risk factors associated with the condition, making this answer comprehensive and correct.

While genetic predisposition can play a role in a person's susceptibility to respiratory conditions, it does not directly cause bronchitis. Similarly, while smoking is a significant irritant associated with bronchitis, the phrasing of the option suggesting it's the only cause is too limiting. Therefore, the broader scope covered by option B is essential for understanding the etiologies of bronchitis effectively.