Final answer:
The signal not naturally shared with dogs is Agnostic pucker. Yawning, play bows, and looking away are behaviors observed in both humans and dogs.
Step-by-step explanation:
The signal that we humans do not naturally share with dogs is B. Agnostic pucker. Signals such as A. Yawning, C. Play bows, and D. Looking away are actions that can be commonly observed in both human and canine behaviors. Yawning can be a sign of empathy and is often contagious between humans and dogs. Play bows are a social cue in dogs to initiate play and can be mimicked by humans during interactions with their pets. Looking away is a gesture that both species use to avoid confrontation or express disinterest. However, the term 'agnostic pucker' is not a recognized signal in canine or human communication and does not describe a natural behavior shared between the two species.
The signal that is not naturally shared with dogs is B. Agnostic pucker. A dog may interpret this expression as a sign of aggression or threat. Dogs can, however, interpret and respond to other signals such as yawning, play bows, and looking away.