Which of the following can cause irreversible obstruction in asthmatics?

Long-standing inflammation is indeed the correct choice for what can cause irreversible obstruction in individuals with asthma. In asthma, chronic inflammation leads to structural changes in the airways, a phenomenon known as airway remodeling. Over time, persistent inflammation can result in the thickening of airway walls, increased mucus production, and loss of elasticity, which ultimately affects airflow and can lead to permanent obstruction.

While acute bronchospasm can cause temporary narrowing of the airways, it is generally reversible with bronchodilators or appropriate treatment. Seasonal allergies may trigger asthma symptoms but do not directly cause permanent airway changes. Inhaled corticosteroids are actually a standard treatment for asthma and help reduce inflammation, thereby preventing long-term airway damage rather than contributing to it.