In which atmospheric layer does most of the greenhouse effect occur answer?

Troposphere

Explanation:

The troposphere is the layer of atmosphere that contain four major greenhouse gases and therefore, is the site for the greenhouse effect. The greenhouse gases present in the lower troposphere are water vapor, carbon dioxide, methane, and nitrous oxide.  

These greenhouse gases trap the radiations reflected back by earth's surface during the night. These trapped radiations serve to increase the earth's atmosphere.  

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.