Final answer:
Antitussives are medications designed to suppress coughing and may include substances like codeine and dextromethorphan, though their effectiveness for all types of coughs, especially in children, has been debated.
Step-by-step explanation:
The drug used to suppress a cough is D. antitussive. Antitussives are cough suppressants that help reduce coughing, often by affecting the cough reflex in the brain. Examples of antitussive medications include codeine and dextromethorphan. While codeine was once regarded highly for this purpose, its effectiveness, especially in children, has been called into question, with some studies suggesting it may be no more effective than a placebo for certain types of cough.