sentence2_structure: A calorie<>is used<>to express the amount of energy in food$$$A calorie<>to express<>the amount of energy
sentence1: In the nutritional literature, the energy content of foods is, by convention, expressed in Calories (note the capital &quot;C&quot;) as opposed to the use of calories or kilojoules (kj) in the scientific literature.
sentence2: A calorie is used to express the amount of energy in food.
question: Which unit is used to express the amount of energy in food?