A Corynebacterium species becomes a pathogen when it produces which of the following?

The correct choice encompasses the various ways in which a Corynebacterium species can exhibit pathogenic behavior. One of the significant factors is the production of an exotoxin, specifically the diphtheria toxin produced by Corynebacterium diphtheriae, which leads to the formation of a pseudomembrane in the oropharynx and can cause severe consequences if not treated.

Additionally, when cultured on Tinsdale's agar, Corynebacterium species can display characteristic growth patterns, such as gray-black colonies with a brown halo, indicating their biochemical activity. Each of these factors is tied to the organism's pathogenic potential, highlighting its role as a human pathogen.

Thus, the inclusion of all these aspects underscores the multifaceted nature of how Corynebacterium can transition from a harmless organism to a significant pathogen, justifying the choice of all available options.