Which of the following is not necessary for the greenhouse effect?

the sun
the atmosphere
the oceans
carbon dioxide

The 'greenhouse effect' is an atmospheric heating phenomenon in which the Earth experiences rise in temperature because certain gases (water vapor, carbon dioxide, nitrous oxide, and methane) in the atmosphere allow incoming sunlight to pass through but trap heat radiated from the earth's surface. But Technically the answer is The Ocean

Americans often speak of their country as one of several large regions.  these regions are cultural units rather than governmental units --  formed by history and geography and shaped by the economics, literature and folkways that all the parts of a region share. what makes one region different from another? a region's multicultural heritage as well as distinct demographic characteristics like age and occupation make regions different and special. within several regions, language is used differently and there are strong dialects. there are also differences in outlook and attitude based on geography.