Final answer:
The characteristic that would be an advantage for a type of dog bred to be a guard dog is a loud bark.
Step-by-step explanation:
The characteristic that would be an advantage for a type of dog that is bred to be a guard dog is loud bark. Dogs were selectively bred for their ability to guard and protect, and part of that process involved selecting dogs who exhibited a bark-howl response when alerted. Wolves, on the other hand, do not call attention to themselves as dogs do and only use barking as an initial alert.