Final answer:
The 'Dirty Dozen' engineers broke with longstanding IBM policy by outsourcing manufacturing, which facilitated the success of the IBM PC in the competitive personal computer market.
Step-by-step explanation:
The 'Dirty Dozen' engineers who designed the IBM PC broke with longstanding IBM policy by c) Outsourcing Manufacturing.
This decision was a significant change from tradition because IBM, historically known for controlling both the manufacturing and software aspects of their computing systems, opted to purchase components from outside suppliers and focus on assembling the PCs.
This initiative contributed to the IBM PC's success and allowed it to quickly secure a dominant position in the burgeoning personal computer market.