Final answer:
During an acute asthma attack, the obstruction is caused by bronchiole smooth muscle spasms.
Step-by-step explanation:
During an acute asthma attack, the obstruction is caused by bronchiole smooth muscle spasms. Asthma is a disease characterized by inflammation and bronchospasms in the airways. During an asthma attack, the smooth muscles in the walls of the bronchioles contract, narrowing the airways and making it difficult to breathe.