Final answer:
Fiscal policy is not a key nutrition concept. Macronutrients, antioxidants, and BMI are related to nutrition, whereas fiscal policy deals with government spending and taxation.
Step-by-step explanation:
The correct answer to the question of which item is not a key nutrition concept is D. Fiscal policy. Nutrition concepts typically involve macro and micronutrients, dietary recommendations, and body composition indicators.
Macronutrients are nutrients that the body needs in relatively large amounts, such as carbohydrates, proteins, lipids, and water. These provide energy for the body, with the exception of water. Antioxidants are substances that can prevent or slow damage to cells caused by free radicals.
The Body mass index (BMI) is a measure used to assess whether a person has a healthy body weight for their height. However, fiscal policy refers to government spending and tax policies and does not relate to key nutrition concepts.