How do master regulatory genes function in cell differentiation?

The choices can be found elsewhere and as follows:

1. They may produce proteins that stimulate production of more of the master regulatory gene. 
2. They are often capable of changing some fully differentiated cells of different types into their particular cell type. 
3. The transcription factors they produce coordinately control related genes. 
4. They produce proteins that act as transcription factors to produce proteins specific to the function of the particular cell type. 
5. All of the above 

I believe the correct answer would be ALL OF THE ABOVE choices. Hope this helps. Have a nice day.

The correct answer is b