The correct option is A Carbohydrates, fats, proteins
The body burns fat after first exhausting the contents of the digestive tract along with glycogen (carbohydrates) reserves stored in muscle and liver cells. During short periods of energy abstinence, the human body will burn primarily free fatty acids from body fat stores. After prolonged periods of starvation when the body has depleted its body fat, it begins to burn lean tissue and muscle (protein) as a fuel source.