When evaluating an animal's aggressive behavior, which of the following signs may be displayed?

When evaluating an animal's aggressive behavior, the signs that may be displayed include growling and showing teeth. These behaviors signal a warning and indicate that the animal may feel threatened or is prepared to defend itself. Growling is a vocalization that often serves as a precursor to more aggressive actions, while showing teeth can be a visual display of intent to be assertive or to bite if the perceived threat does not back down.

In contrast, whining and hiding suggest fear or anxiety, barking and wagging the tail can demonstrate excitement or happiness rather than aggression, and climbing and jumping are not typical behaviors associated with aggression. Instead, these actions may indicate playfulness or exploration, which are not aligned with signs of aggression. Thus, growling and showing teeth are clear indicators of an animal's readiness to engage in aggressive behavior, making this the correct choice.