Which behavior best describes an aggressive dog?

The behavior that best describes an aggressive dog includes a clear display of aggressive actions, such as lunging and biting. These behaviors indicate that the dog is not just being protective or territorial but is actively trying to threaten or harm. Aggression in dogs often manifests through body language such as growling, baring teeth, or exhibiting a tense stance, and lunging is a direct action that suggests the dog is ready to strike. Biting represents a physical manifestation of that aggression and can cause serious harm, which distinguishes aggressive behavior from other forms of canine actions.

In contrast, friendly interactions with joggers, casual observation of runners, and a cuddly demeanor all suggest non-aggressive behaviors that indicate comfort, playfulness, or sociability. None of these interactions involve the threat or intent to cause harm, which is essential in discerning aggressive behavior.