MSFinals-5883

A 32-year-old office worker attends Asthma Clinic for her annual asthma review. She takes a steroid inhaler twice daily, which seems to control her asthma well. Occasionally, she needs to use her salbutamol inhaler, particularly if she has been exposed to allergens.
What is the primary mechanism of action of the drug salbutamol in the treatment of asthma?