The correct answer is B. A geography textbook
Step-by-step explanation:
In texts, the tone refers to the attitude of the speaker towards the main topic or subject he or she writes about. In the case of a formal tone, this tone occurs if the attitude of the author is serious, academic, objective and distant from the reader. According to this, the type of nonfiction text that is likely to have a formal tone is a geography textbook because different to other texts such as a guidebook or a blog, a geography textbook is mainly academic, and in this the tone of the author is always serious, objective or formal, while in others the author can be more conversational or informal to engage the reader.