Why was having a written law code a victory for the plebeian of Rome?

1. It encouraged the upper class to make laws that benefited them.
   
2. It allowed them to overthrow the patricians and gain power for themselves.
   
3. It ensured that laws were enforced equally for all social classes.
   
4. It provided them with opportunities to seize power from the dictators.
   

Please give clear answers and don't make you're answer too thick, I won't be able to understand if so. If you aren't sure, don't answer please. I need as much HELP as possible though.