How does ATP RELEASE its energy to the cell?

Cells can store energy by adding phosphate groups to ADP. This then produces ATP. They can then release stored energy in ATP by breaking the bonds in the phosphate groups.

c is the answer because when something is left after something evaporates that shows the chemical change.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.