Reasonable nutrition refers to comprehensive and balanced nutrition. "Comprehensive" refers to the complete intake of nutrients; "Balance" means that the intake of various nutrients should be appropriate and balanced with the needs of the body. In order to achieve reasonable nutrition, nutritionists in China divide foods into five categories and visually design them as "balanced diet pagodas" to encourage residents to eat these five types of foods in a balanced way every day to avoid malnutrition and overnutrition. "Balanced Diet Pagoda" represents the approximate proportion of five kinds of food from "bottom of the tower" to "top of the tower". The second layer is vegetables and fruits, which mainly provide vitamin C; The third layer is fish, meat and eggs, the fourth layer is soybean milk, and the third and fourth layers mainly provide protein and calcium; The fifth layer is grease, which mainly provides fat. The basic principles of "Dietary Guide for China Residents" point out that: the food is diverse, mainly cereals, and the thickness is matched; Eat more vegetables, fruits and potatoes; Eat milk, soybeans or their products every day; Eat proper amount of fish, poultry, eggs and lean meat; Reduce the consumption of edible oil, and the diet is light and salt-free.

So choose: a.