Final answer:
The appropriate term for firms partnering across the value chain is a horizontal complementary strategic alliance, involving cooperation between firms at different stages of production to maximise efficiency and share risks.
Step-by-step explanation:
The concept of firms partnering across the value chain represents a business strategy where companies at different stages of the production process join forces. This is known as a horizontal complementary strategic alliance, where firms that operate in parallel or related industries but at different levels of the value chain partner to leverage each other's strengths, share risks, and create synergies. Examples include a car manufacturer partnering with a tire company or a smartphone company collaborating with software developers.
While a franchise is a form of business expansion allowing an entity to operate under the franchisor's name and business model, it is not the correct term for a value chain partnership. Vertical mergers are not considered either, as they involve companies at different stages within the same industry combining, such as a supplier merging with a retailer. And while a conglomerate involves the ownership of businesses in unrelated industries, it does not specifically relate to partnerships across the value chain.
As for the synergistic strategic alliance, it is a broader term that can include horizontal complementary alliances but is not specific to value chains. Thus, the final answer is a horizontal complementary strategic alliance, as it accurately describes the partnership between companies at different stages of the value chain for mutual benefit.