A Patient Who Has Seasonal Allergic Rhinitis Is Having a Flare

A patient who has seasonal allergic rhinitis is having a flare up and is complaining of sneezing and a watery, runny nose (rhinorrhea) . The patient is prescribed an antihistamine. The expected effect of this medication is to:

A) promote blood flow to the area to remove inflammatory mediators.
B) promote smooth muscle contraction thereby improving drainage.
C) decrease vascular permeability to decrease rhinorrhea.
D) increase vascular permeability to allow for improved drainage.