Question

what is a calorie?
the amount of energy in the form of heat that it takes to raise the temperature of 1 gram of water 1 degree celsius
a unit of energy that is used to show how nutritious certain foods are
a vital nutrient that all animals require for survival

Explanation:

A calorie is defined as the amount of energy in the form of heat required to raise the temperature of 1 gram of water by 1 degree Celsius. It is also used as a unit to measure the energy content in foods, which indicates their nutritional value in terms of energy - not as a nutrient itself.

Answer:

The amount of energy in the form of heat that it takes to raise the temperature of 1 gram of water 1 degree Celsius, A unit of energy that is used to show how nutritious certain foods are