Answer:
Among the options provided, the most accurate answer would be:
c. Cook had been a successful manager of operations, and then COO.
Tim Cook's experience and success as Apple's Chief Operating Officer (COO) played a significant role in his selection as Steve Jobs' successor as CEO. Cook was responsible for managing Apple's global supply chain and operations, which involved streamlining processes, improving efficiency, and ensuring the company's products were delivered on time. His operational expertise and ability to navigate complex logistics were highly valued, as they contributed to Apple's overall success.