Which of the following is considered a fault for a cavy at a show?

The concept of faults in cavy shows refers to specific criteria that can negatively impact a cavy's performance or acceptance in the show ring. In this case, color placement is deemed a fault because each breed of cavy has certain breed standards that define acceptable colors and patterns. When a cavy's color does not comply with these standards, it can be considered a fault during the judging process.

On the other hand, shorter than average fur is typically evaluated against the breed's standard. Therefore, while it may not be ideal or might affect appearance, it may not directly lead to being categorized as a fault depending on the breed’s specific requirements. Excessive weight can be a concern in terms of overall health and well-being, but it does not always classify as an official fault. Well-defined markings are generally favored in certain breeds, as they contribute positively to the cavy’s visual appeal, rather than being a detriment. Thus, the focus on color placement aligns directly with show standards and criteria, making it a recognized fault.