Final answer:
Animals get iatrogenic disease as a result of medical treatment (Option C), not from genetics, other infections, or environmental factors. It occurs when medical procedures inadvertently introduce pathogens, leading to disease.
Step-by-step explanation:
Animals get iatrogenic disease due to medical treatment (C). An iatrogenic disease can occur after medical procedures such as wound treatments, catheterization, or surgeries especially if a wound or surgical site becomes contaminated. An example of an iatrogenic disease is necrotizing fasciitis, which can develop if bandages become contaminated by bacteria such as Clostridium perfringens. These diseases are distinct from those acquired in hospital settings, which are known as nosocomial diseases. Factors like the presence of pathogens, weakened immune systems of patients, and the prevalence of antibiotic-resistant bacteria contribute to these conditions.
On the other hand, animals do not get iatrogenic diseases due to genetics (A), infection from other sources such as dog bites (D), or environmental factors (D). It is specifically the result of medical treatment that can lead to iatrogenic diseases.