Identify a true statement about responsive supply chains.

a. They use only a few, large distribution centers to generate economies of scale.
b. They use optimization models that minimize costs of routing products from factory through distribution centers to retail stores and customers.
c. They are designed for efficiency and low cost by minimizing inventory and maximizing efficiencies in process flow.
d. They are supported by information technology that provides real-time information to managers across the supply chain.