Most climate scientists agree the main cause of the current global warming trend is human expansion of the "greenhouse effect"1 — warming that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere block heat from escaping.
Based on this exert, I'd say Option C
it dates back to the Precambrian era
The first step in designing an experiment is the form a testable question.
Metamorphic rocks are formed from existing rocks, when it is exposed to great heat and pressure. This process would destroy any fossils inside the already existing rock.
