Was prohibition responsible for the rise of al capone

Yes. He had just risen to be the leader of Torrio's gang. His arrival to chicago changed the business climate as he was wrapped in a web of illegal activities which involved production and distribution of alcohol and other illegal items both home and from abroad. He had a chain of bodyguards and bribed the law enforcement agents and also high profile politicians so as to protect himself and his investments. When prohibition law was ratified he basically was in control of lots of businesses involved in the production of illegal items like alcohol and since he had a tonne of money to bribe his way out. He used profit from these to invest in other businesses like gambling spots and others.