Final answer:
The selective agar medium for Bordetella pertussis is Bordet-Gengou medium, supplemented with blood and antibiotics to favor the growth of the pathogen while inhibiting others.
Step-by-step explanation:
The selective agar medium for Bordetella pertussis, which is the pathogen responsible for pertussis (whooping cough), is Bordet-Gengou medium. Bordet-Gengou medium is enriched with blood and contains antibiotics such as cephalexin to suppress the growth of contaminating bacteria. It is specifically designed to isolate B. pertussis from nasopharyngeal specimens by providing nutrients that support its growth while inhibiting the growth of competing microorganisms.