During an Acute Asthma Attack, How Does Respiratory Obstruction Occur

Multiple Choice

During an acute asthma attack, how does respiratory obstruction occur?
1) Relaxation of bronchial smooth muscle
2) Edema of the mucosa
3) Increased secretion of thick, tenacious mucus
4) Contraction of elastic fibers

A) 1, 2
B) 1, 3
C) 2, 3
D) 2, 4