Why does the author include the detail “orange soda and root beer are both sweet, cold, and bubbly, but they do not taste the same.” ?

Immediately after the detail in paragraph 3, the author states that you also need to use your sense of smell in order to get the full flavor of your food. The detail regarding orange soda introduces the necessity of the olfactory system by providing an example.
To support the idea that receptors can tell whether a food is sweet is incorrect. Although it is true that receptors can tell whether a food is sweet, it is not the reasoning behind this supporting detail, as the example does not mention receptors.
To provide an example of sending the full flavor to the brain is incorrect. Examples of the full flavor of food, nor the process of sending flavors to the brain are included in this example.
To support the idea that being able to understand flavor is not truly tasting food is incorrect. While the detail discusses the sweet flavor of different types of soda, it does not state the inability of tasting food.