Final answer:
The author's tone in the passage about redirecting a dog's biting behavior is informal, characterized by the use of conversational and friendly language.
Step-by-step explanation:
The author's tone in the playful pooch passage is informal. This tone is reflected in the conversational and friendly manner of the writing, which aims to educate the reader on how to redirect their dog's biting behavior in a non-confrontational way. Phrases like "playful pooch" and "canine companion" enhance the informal and pleasant tone of the passage. There is no evidence of sarcasm or scientific jargon, and the tone is not overly formal.