The answer is B to the question
The amount of atomic mass between them
global warming is a increase in earths overall temperture caused increased levels of carbon dioxide, chlorofluorocarbons, and other pollutants.
to prevent global warming we could:
Drive less, Recycle more, Use less hot water, Plant a tree, Turn off electronic devices when not being used such as a T.V
all of these ideas save pounds of carbon dixoide and if you look above it is listed as a cause of global warming
i think A would be right if they are taking ab the scientific method