Correct Answer: D

Rationale: The correct answer is D, water. Water plays a crucial role in metabolic regulation along with vitamins and minerals. While amino acids, carbohydrates, and fats are essential nutrients for various bodily functions, they are not primarily involved in metabolic regulation and control.

Correct Answer: A

Rationale: The correct answer is A: Vitamins. Vitamins play a crucial role in tissue building and repair along with protein. Carbohydrates (choice B) are primarily a source of energy and not directly involved in tissue building. Fats (choice C) are important for energy storage and insulation but are not the main contributors to tissue building. Enzymes (choice D) are biological catalysts and do not directly contribute to tissue building and repair.

Correct Answer: B

Rationale: The correct answer is B: 'fulfill specific metabolic roles.' Nutrients play essential roles in specific metabolic processes in the body such as energy production, tissue repair, and growth. Choice A, 'work independently,' is incorrect as nutrients often work synergistically rather than alone. Choice C, 'influence weight loss,' is incorrect as while some nutrients may support weight loss indirectly through metabolic processes, it is not their primary characteristic. Choice D, 'improve mental status,' is also incorrect as while some nutrients are important for brain health, their primary role is not specifically to improve mental status.

Correct Answer: A

Rationale: The correct answer is A: potassium and vitamin A. Vegetables are an excellent source of potassium and vitamin A, both essential for maintaining overall health. Iron and vitamin C (choice B) are commonly found in foods from the Protein and Fruits groups, respectively. Calcium and vitamin B12 (choice C) are more abundant in dairy products and animal-based foods. Sodium and vitamin E (choice D) are not the major nutrients typically supplied by vegetables.

Correct Answer: B

Rationale: A variety of foods is the best source of nutrients because it ensures a balanced intake of all essential nutrients required by the body. Option A, specific food combinations, may not provide all necessary nutrients as relying on only a few types of food may lead to deficiencies. Option C, individual foods, also may not provide a complete range of nutrients necessary for overall health. Option D, a variety of food supplements, is not the best source of nutrients as whole foods are generally more beneficial due to their natural nutrient composition and bioavailability.