Adidas has experienced growth through its innovative approaches to sport sponsorship, a commitment to an ethical global supply chain, and new developments in its mobile-phone app, online supply chain, and manufacturing technologies. These successes are best supported by which implication for action for savvy managers?

a. Managers need to build up resources and capabilities for future competition.

b. Relentless imitation or benchmarking, while important, is not likely to be a successful strategy.

c. Students need to make themselves into "untouchables" whose jobs cannot be easily outsourced.

d. Managers need to build firm strengths based on the VRIO framework.