Test and analysis: The food contains protein, sugar, fat, vitamins, water and inorganic salts. Sugar, fat and protein are the main components of cells, which can provide energy for life activities. Sugar is the main energy-supplying substance, which can provide energy for human body; Protein is the basic substance of human cells, which has an important relationship with human growth, cell repair and renewal, and can also provide a small amount of energy; Fat is a kind of energy storage substance, which is generally stored under the skin for later use, so sugar, fat and protein are called the three major thermogenic nutrients. Vitamins neither constitute human tissue cells nor provide energy, but they are important substances to regulate human life activities; Inorganic salts are important substances that constitute human tissues; Water is an important part of human cells and participates in regulating life activities. So option c fits the question.