With respect to calories what is the difference between 'C' and 'c'?

• A. One is for food calories and the other is for heat calories
• B. They are the same
• C. Capital C is energy and lowercase c is speed of light
• D. Lowercase c is calories

Answer: (A)

Calories come in two closely related but distinct units. On food labels, a capital C Calories are used, and they’re actually kilocalories—the energy you get from food. One Calorie equals 1000 of the small calories (lowercase c) used in physics. The lowercase calorie is the unit scientists use to measure heat energy, defined as the amount of energy needed to raise 1 gram of water by 1 degree Celsius. So the capital-C Calories you see on nutrition facts indicate dietary energy, while the lowercase c calories are the smaller energy unit used in thermodynamics and heat calculations. That’s why they’re not the same quantity, and why the option describing one as food energy and the other as heat energy is the correct distinction. The other statements mix up units or contexts (for example, equating lowercase c with speed of light or claiming they’re identical), which isn’t accurate.