Which macronutrient primarily fuels activity and supports muscle repair and adaptation?

• A. Fats provide the primary fuel for most activities.
• B. Carbohydrates fuel activity; protein supports muscle repair; fats provide energy; targets depend on activity but carbs 5–7 g/kg/day, protein 1.2–2.0 g/kg/day, fats remaining energy needs.
• C. Protein provides the main energy source during workouts.
• D. Vitamins are the main source of energy.

Answer: (B)