According to botanists, who study and classify plants, a fruit is the part of a plant that contains seeds. By this definition, not only melons and plums but zucchinis, green beans, and tomatoes are all fruits. In fact, based on this definition, any vegetable with seeds could be classified as a fruit. In contrast, nutritionists, who study diet, reserve the term "fruit" only for sweet, fleshy fruits, using "vegetable" for those that are low in fructose, or fruit sugar. Vegetables are usually eaten as part of a meal, while fruits are often eaten as a snack or dessert. Nutritionists argue that although tomatoes may be fruits from a botanical perspective, they aren't eaten the way typical fruits are, so they're vegetables. Depending on who you ask, a tomato can be considered a fruit, a vegetable, or both. What is the main idea of the passage?