Final answer:
Fats have the highest calorific value at approximately 9 calories per gram, compared to both proteins and carbohydrates, which each provide about 4 calories per gram.
Step-by-step explanation:
Among the options provided for which nutrient has the highest calorific value, the answer is C. Fats. Macronutrients are essential components of our diet, and among them are carbohydrates, proteins, and fats or oils. Each of these nutrients provides different amounts of energy, measured in calories per gram.
Both proteins and carbohydrates provide about 4 calories per gram, whereas fats provide roughly 9 calories per gram. This makes fats the most calorific of the macronutrients and is why they serve as the primary energy store for the body. Consuming more energy than the body's requirements leads to the excess being stored as fat deposits, highlighting the importance of balancing intake with physical activity.