Final answer:
Sonny Barger centralized the Hells Angels' structure and established chapters worldwide, creating a more organized and powerful motorcycle club.
Step-by-step explanation:
Sonny Barger, a pivotal figure in the history of the Hells Angels Motorcycle Club, played a significant role in transforming the club. The accurate answer to how he transformed the Hells Angels is that he centralized the gang's structure and established chapters worldwide. Barger was instrumental in organizing the club's chapters under a single set of rules and thus founded one of the world's most notorious motorcycle clubs.