An example of _____ is the bacterium Moraxella bovis, the etiologic agent of pinkeye.

Moraxella bovis is identified as the etiologic agent of pinkeye, which refers to the specific bacterial cause of the disease. In this context, the correct term to fill in the blank would relate to a specific process involving the pathogen's behavior or impact on its host. Phoresis, which implies a specific kind of mutualism where one organism (in this case, the bacterium) is transported by another, does not capture the essential nature of the relationship in terms of disease causation.

The correct answer reflects the role of Moraxella bovis as an organism that can establish a pathogenic association, leading to clinical disease. Understanding the etiology of a disease like pinkeye requires recognizing the bacteria's role in causing infection. Phoresis does not encompass the broad implications of pathogenicity and disease development that infection includes.

In veterinary pharmacology and disease management, recognizing the characteristics of infectious agents like Moraxella bovis is crucial. It’s important for practitioners to differentiate between various biological interactions, such as infection (where a pathogen invades and multiplies within a host), transmission (the process by which pathogens spread), and infestation (typically related to larger organisms, such as parasites).