Final answer:
The effectiveness of generic business-level strategies depends on the match between external opportunities and threats, internal strengths, market needs, and competitive advantage.
Step-by-step explanation:
The effectiveness of any of the generic business-level strategies is contingent upon the match between the opportunities and threats in its external market and the strengths of its internal environment. In other words, a company's strategy should align with the needs of its customers and the competition in the market (option a), but it should also take into consideration the external factors such as market trends, consumer base, and economy (option c). Additionally, the company's strategy should be based on its competitive scope and advantage (option d).