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 categories of foods in a balanced way every day to avoid malnutrition and overnutrition. "Balanced diet pagodas" represent the approximate proportion of the five categories of foods from "tower base" to "tower top". The second layer is vegetables and fruits, which mainly provide vitamin C; The third layer is fish, meat and eggs, the fourth layer is soy milk, and the third and fourth layers mainly provide protein and calcium; The fifth layer is oils and fats, which mainly provide fats. The basic principles of "Dietary Guide for China Residents" point out that: foods are 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 amount of cooking oil and eat a light and salt-free diet.

So choose: a.