Which of the following is a mast cell stabilizer used for allergic rhinitis?

Cromolyn is a mast cell stabilizer that is specifically indicated for the management of allergic rhinitis. It works by preventing the release of histamine and other inflammatory mediators from mast cells, thereby reducing symptoms associated with allergies such as nasal congestion, sneezing, and itching. This mechanism helps to stabilize mast cells and prevent allergy-related responses when exposure to allergens occurs.

In contrast, oxymetazoline and phenylephrine are decongestants that provide symptomatic relief by vasoconstriction of nasal blood vessels, reducing nasal congestion. These do not have the same preventive effect against allergic reactions as cromolyn does. Clindamycin, on the other hand, is an antibiotic and is not used for allergic conditions; it is effective against bacterial infections and would not have any role in managing allergic rhinitis. Thus, the role of cromolyn as a mast cell stabilizer is crucial in the context of treating allergic responses.