Dietetics (营养学) is the application of the science of nutrition (营养) to the selection and preparation of foods, in health and disease. A dietitian is specially trained to give practical advice to individuals about their diets. He l she will have received training in a hospital and / or community setting as part of his / her course. Many dietitians are employed in the NHS (National Health Service). They work with both healthy and sick people, as well as their families. With patients who need special diets, dietitians use their scientific knowledge to provide practical information that is appropriate to the patient’s medical history and lifestyle.These days a large number of dietitians spend some or all of their time working in the .community rather than in a hospital. Many of these have full conditions to apply for registration in public health nutrition as well as being registered dietitians (RD). In the community, the dietitian’s work is more about health education, although many also run clinics (诊所) for people who need specialists’ suggestions about the right diet. Dietitians also work in research, the food industry, government, the media and education. Information about part-time dietitians is available from the Freelance Dietitians Group of the British Dietetic Association.It is necessary to have a degree (BSc or MSc) in nutrition and dietetics to work as a dietitian. The British Dietetic Association has information about qualifying as a dietitian. There exist undergraduate and postgraduate degrees for a qualified dietitian who has finished required courses. According to the passage, which of the following does dietetics NOT refer to（）

A. It uses the science of nutrition to construct diets in health and disease.
B. It uses the science of nutrition to select foods.
C. It uses the science of nutrition to create diets only for patients.
D. It uses the science of nutrition to prepare foods.