When Someone Has a Sinus Headache He or She Often

When someone has a sinus headache he or she often uses decongestant nasal sprays.Why are such sprays useful?

A) They reduce swelling, allowing the sinuses to drain.
B) They reduce the symptoms of sore throat inflammation, which exacerbates the pain.
C) They dry out the breathing passageways in the pharynx, making it easier to breathe.
D) They have a pain-blocking effect in the brain.