I believe C is the correct answer; parent material is rich in nutrients for plants, and decomposed plant litter is also known as decaying organic material. Hope this helps! :)
This statement is true. Soil color only reflects the amount of organic matter that is currently present in the soil. If the soil seemed to be much darker, it means that the soil has a greater amount of organic materials which makes it better.
A green card doesn't have anything to do with citizenship, but is important if you want to stay here for a long time without committing to a citizenship. If you are ready, take the citizenship test. If not then get a visa or green card and take a course to become a citizen.