Concept:A balanced diet means eating food containing all needed nutrients in the right proportions.Explanation:Option A is correct because it mentions the food nutrients should be in the right proportions.Option B is wrong because balanced diet does not mean equal amounts of nutrients.Options C and D are incomplete because a balanced diet includes all nutrients, not only water and salt or only vegetables, fruits, and water.Answer:A. right proportions of protein, carbohydrates and oils.