What type of aggression is displayed when an animal protects its owner?

The correct choice is protective aggression. This form of aggression occurs when an animal perceives a threat to its owner or protector and reacts defensively to safeguard them. Dogs and other pets often display this behavior when they sense danger or potential harm to a person they are closely bonded with.

In contrast, fear aggression stems from an animal's fear or anxiety, leading it to act aggressively to protect itself. Territorial aggression is exhibited when an animal feels the need to protect its space or territory against intruders. Social aggression usually involves competition for social standing or resources among animals. Each of these types of aggression is distinct and is triggered by different stimuli, but in this case, the intent to protect an owner categorizes the behavior as protective aggression.