A patient who has hypertension and mild asthma attacks bought a herbal remedy for asthma online. He does not take any prescription medications for asthma, but takes a B1-selective blocker for hypertension. The herbal remedy relieves the asthma attacks, but his blood pressure seems to increase despite the B-blocker therapy. Which of the following drugs is most likely present in the herbal remedy?
a. Phenylephrine
b. Norepinephrine
c. Ephedrine
d. Salmeterol