Final answer:
Jupiter Inc. should focus on making its software more user-friendly than Coral Inc.'s to retain customers. Other options like keeping higher costs or limiting complements are not as effective. Predatory pricing is an illegal practice and should be avoided.
Step-by-step explanation:
To ensure Jupiter Inc. retains its customer base in the face of competition from Coral Inc., the best measure to adopt would be A. Ensuring that customers find its software simpler and more convenient to use than that of Coral. This approach focuses on improving user experience to maintain customer loyalty. Options B, C, and D, which involve keeping costs higher or limiting complementary products, are more likely to deter customers and potentially push them towards competitors. Instead, focusing on enhancing the value of Jupiter's software can lead to an improved competitive edge.
Business strategies such as predatory pricing could be considered, which involves price cuts to discourage competition. However, predatory pricing is illegal under U.S. antitrust laws and not advisable as a business strategy. A more sustainable approach would be to innovate, improve service and quality, or use customer feedback to outpace the competitor's offerings, which can help retain customers without violating any laws.