Final answer:
Nutrients are needed for body functions, including maintenance, temperature regulation, digestion, and work. Option a is correct.
Step-by-step explanation:
Nutrients such as carbohydrates, proteins, lipids, and water are required for various body functions, including maintenance, temperature regulation, digestion, and work. These are needed in large amounts and are considered macronutrients.
On the other hand, vitamins and minerals are also essential but needed in much smaller amounts. Vitamins function as coenzymes and assist enzymes in catalyzing reactions, which is vital for energy metabolism, blood renewal, and other functions.
However, contrary to statement 9a from the provided information, essential nutrients, like some vitamins, cannot be synthesized by the body and hence must be obtained from our diet. Vitamins A and K are such fat-soluble essential vitamins, where Vitamin A is crucial for maintaining connective tissue, and Vitamin K is necessary for blood clotting.
It is key to maintain a balanced diet as it provides both nutrients and vitamins that contribute to maintaining good health and reproductive capability. The correct answer to the question is nutrients are needed for body functions, including maintenance, temperature regulation, digestion, and work.