Question 1
Where does carbon dioxide come from?

Atmospheric carbon dioxide derives from multiple natural sources including volcanic outgassing, the combustion of organic matter, and the respiration processes of living aerobic organisms; man-made sources of carbon dioxide come mainly from the burning of various fossil fuels for power generation and transport use.

Explanation:

Carbon dioxide (CO₂) is a colourless and odourless gas that is a natural component of our air and makes up part of the carbon cycle.

Through the decomposition of organic matter, CO₂ is released into the atmosphere as part of this natural process. At the same time, photosynthesis helps to significantly reduce atmospheric CO₂ . The solubility of CO₂ in water depends on the temperature, so the oceans both produce and reduce CO₂. 

Anthropogenic (man-made) carbon dioxide sources primarily relate to the combustion processes of fossil fuels. CO₂ is an inert end product that accumulates in the atmosphere and is in constant exchange with the biosphere and the oceans. Carbon dioxide reacts with water to form carbonic acid or hydrogen carbonate, which leads to a change in the pH value, i.e. the acidity of the water. Other anthropogenic CO₂ sources that intensify the greenhouse effect include changes to land usage, e.g. the clearing of forests or draining of wetlands such as moors.

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.