Answer:
Sigma factors bind to the promoter region of a particular gene and facilitating the binding of RNA Polymerase to the promoter region (formation of the RNA polymerase holoenzyme complex) in order initiate transcription of the gene.
Put simply - Helps RNA Polymerase do it's job.
In a human? Need more context here but should be outside the cell. At equilibrium you will have a more negative environment in the cell.
I believe that a scientific journal would be the best way to communicate towards his other colleague's. The reason why I wouldn't say the internet is, although the internet is much faster compared to others, the internet can differ in in information, making it unreliable.
Blocking the way upstream
The answer is D. Carbon cycle
