What is a potential reason for including “Have you ever looked at your tongue in a mirror?” as the first sentence of the passage?

Opening with a question directly involves the reader and sets up the context for explaining the bumps on one’s tongue in the opening paragraph. The question is a rhetorical one, and it is designed to get the reader thinking about their own tongue and the way it feels. The passage then goes on to explain that the bumps on the tongue are called papillae and that they contain hundreds of taste buds.
To introduce the fact of having taste buds on the roof of the mouth is incorrect. While the introductory question sets up the context for bumps on the tongue, it does not directly involve setting up the context for the taste buds on the roof of the mouth.
To provide an introduction regarding the olfactory receptors is incorrect. Olfactory receptors are discussed later in the text and do not have a direct connection with the opening sentence.
To provide context to the idea of eating and chewing for paragraph 3 is incorrect. The introductory question regards taste buds and the introductory sentence regarding eating and chewing is further developed in paragraph 2.