Which one of the following statements about croup is true?

A) The classic presentation of croup is the onset of a "seal bark" at night.
B) The child with croup mostly has wheezing while he is active or playing during the day.
C) Croup is a bacterial infection that causes swelling of the epiglottis.
D) It is not an emergency, although first-time parents can become very alarmed by it.

A