How Are Complex Processes Such as Sporulation,synthesis of Flagella,and Nitrogen

How are complex processes such as sporulation,synthesis of flagella,and nitrogen fixation that require the transcription of multiple sets of genes regulated in bacteria?

A) Multiple operons are simultaneously induced.
B) A hormone activates transcription of each gene simultaneously.
C) The end product of one operon is used as an inducer of the next operon in sequence.
D) There are single operons consisting of many genes for each of these processes.
E) Cascades of sigma factors synthesized in a temporal order,allow the turning on of successive sets of genes.