Cell , tissue , organ, organ systems , organism
If you mean periodic table then it would be atomic number
I think none of the men are the father, they don’t match the child’s results.
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.