Cells are the smallest living thing and they are what form everything living. they are the same as atoms but the living kind?
The answer should be the third option "number of protons and neutrons." The atomic mass of a element is equal to the amount of protons, and neutrons added together in that element. So for example if we are trying to find the atomic mass of hydrogen you would add the total amount of protons and neutrons together to find it's mass although it doesn't equal the exact amount of it's mass but it's close.
Hope this helps.
You will some water vapour
I filled out a few boxes for you to start you off. I also gave you a direct research sources for some animals that will take you to the necessary information.
This is what I have so far as examples for you. Again, I said I wouldn't do all of your work for you, however, I will help you through your research and graph.