Epiglottitis, a Severe Life-Threatening Infection Occurring in Non-Vaccinated Infants and Children

Epiglottitis, a severe life-threatening infection occurring in non-vaccinated infants and children, is most commonly caused by

A) a pleomorphic gram-negative coccobacillus that is ALA positive and horse blood agar positive.
B) a gram-negative coccobacillus that is identified by direct fluorescent antibody and slide agglutination tests.
C) a gram-negative coccobacillus that is best identified by a rise in antibody titer in serum samples drawn two weeks apart.
D) a pleomorphic gram-negative coccobacillus that requires X and V factors and is horse blood agar negative.