Answer:
Option B. Prevent or relieve coughing.
Step-by-step explanation:
Antitussive medication are used when the patient experiences a persistent cough that is potentially affective quality of life or ability to perform activities of daily living. A common antitussive is dextromethorphan. The goal of these medications is to make the cough less frequent and less intense without getting rid of the useful cough reflex entirely -- we do not want patient to be unable to expel potential choking hazards. So the closest answer to this is option B.
Option A is describing a bactericidal antimicrobial or anti-infective such as vancomycin. Option C is describing an antihistamine, most of which do NOT block histamine release; rather, they block the effects of histamine at the receptor site. Option D seems like it could be describing a corticosteroid or steroidal anti-inflammatory agent like fluticasone.